View Full Version : Cam for my 350 TBI truck


woody80z28
05-17-2011, 01:07:50 PM
My truck needs some more power...it's a stock 94 350 TBI. Should be 9.2:1 compression with the stock wimpy cam. It's 4500lbs with a stock converter, 3.73 gears and 33" tires.

Looking at cams and trying to decide between a couple: Comp 12-249-4 and 12-231-2. I tried Comp's "CamQuest" and it came up with the 249 with the honest specs I gave it and estimated dyno numbers of 378lbft at 2000 and 262hp at 4000. Seems a little optimistic to me, but that would be great!

I'm definitely adding long tubes and a good new cat to hook up to my 3" mandrel exhaust. Also thinking about Vortec heads and an intake. Anybody have experience doing this stuff to a TBI? Any recommendations. I'd like to keep a low budget since it is my beater, but figured since I'm replacing the trans I might as well do something about the gutlessness problem.

AJ_72
05-17-2011, 01:27:01 PM
Actually, I have to perfect cam for you.

It's a stock LT1 cam out of a '94 Trans Am.

PM me if you're interested.

BondoSpecial
05-17-2011, 01:32:03 PM
^+1 I am running the larger LT1 cam (.449/.459 117 LSA) whatever year that was, in my 350 TPI 5200 lb K1500 and it PULLS. Part of why it runs so well was getting rid of TBI but it is a super mild cam and I'm sure it would be a big improvement even under a TBI setup.

Alex71RS
05-17-2011, 02:10:51 PM
I think the 12-249-4 is better cam between the two you listed. The duration @ .050 is good (206/212) and the lobe seperation (112) is also good. The LT1 cam is also a good choice as well.

For a TBI application, the number to be the most concerned with is the duration @ .050. Anything over 220 @ .050 on a TBI will cause the MAP sensor to go nuts because the MAP wants to keep the vacuum within a certain range (which if I remember correctly is 17-19 inches). The bigger the .050 number is, the longer the valve will be off the seat (hence the term duration), which will affect vacuum. The second most important number to look for is the lobe seperation, which is the distance in degrees, as measured on the cam, between the point of peak lift on the intake lobe and the peak lift on the exhaust lobe. The higher the lobe seperation number, the better the vacuum signal, the broader the powerband, and the better the idle quality. If you look at a factory GM cam, the lobe seperation on the computer cars is usually 114 or higher, mostly due to the MAP sensor's desire for an optimum vacuum number.

You can step slightly out of bounds when choosing a cam for a TBI, but you have to be careful. Too high a duration or too low of a lobe seperation will cause the MAP sensor to go nuts. What will happen is that the MAP will be trying to find the best vacuum number and it'll be sending that data to the computer, which will tell the IAC (idle area controller) to speed the idle. The idle will go up and down, up and down, and never settle. You can have your MAP reflashed to account for it, but the computer system never seems happy even after that's done. The TBI systems were designed for fuel mileage, torque, and snappy throttle response. They can be made to run better, but they were never meant to be fire-breathers.

I did a ton of research when I was going to retrofit a TBI into a mid-70s Chevy truck years ago. I had everything to mod the truck, but wound up selling it before it ever happened. All my TBI stuff went on ebay, and the buyer got a smoking deal on some great parts. It would have been a really nice mod.

Ironically enough, the cam I was planning to run was the LT1 cam...

BondoSpecial
05-17-2011, 02:14:19 PM
MAP data is used for a whole hell of a lot more than idle speed. I think woody has tuning equipment and plans on tuning this appropriately.

Lowend
05-17-2011, 02:33:22 PM
Keep the Lobe Seperation WIDE like 114 - 116 deg and duration under 220@050

Does this truck have the factory roller cam?

BondoSpecial
05-17-2011, 02:54:38 PM
TBI trucks never had a roller cam. But the block may be roller ready, some are, some aren't. If it is roller ready by all means use a roller cam.

woody80z28
05-17-2011, 03:23:44 PM
The LT1 is a roller cam I assume, correct? I haven't opened up the block to know if it's roller-ready yet, but I wouldn't be opposed to using a roller cam...they are definitely better technology, and I'm assuming the stock spider & lifters, etc aren't that expensive. However, if it's not roller-ready I'll stick with flat tappet, since this is my beater/hauler. The Comp "X" cams have pretty aggressive lobes for a flat tappet anyway, so it will be much better than stock either way.

I'm familiar with OBD1 and I will be tuning. I know I want to keep the cam conservative for low end torque anyway. This pig is heavy, and the TBI truck heads can't support a big cam even if I did want to RPM it.

BondoSpecial
05-17-2011, 03:29:59 PM
the really early TBI trucks were not necessarily roller cam ready blocks (my 88 wasn't) but a 94 I would expect would be (I have a 93 K series block and it was roller ready). The LT1 is a roller cam. I paid $40 for my cam and another 50 or 60 recently for a nice used set of lifters, spider, dog bones, and wear plate.

The casting # of the block can be looked up online and will tell you if it was a roller ready block or not (the # on top rear near the distributor)

woody80z28
05-17-2011, 03:38:04 PM
I'll see if I can get that casting #. I have a few weeks before I can tear into it, and it would be nice to know before hand.

BondoSpecial
05-17-2011, 04:07:30 PM
yeah you should be able to read it in the truck and I'll see if I can find the site that told you what 80s-90s block casting #s came pre machined for roller cam hardware.

Damon
05-17-2011, 06:02:04 PM
If you can go roller with the block, definitely consider a used LT1 roller cam. You can even use the stock springs with them up to about 5000 RPMs.

If you have to go flat tappet, I'd make a few suggestions. First off, the TBI heads have a pretty bad intake port (swirl port) but a fairly decent exhaust port (ever bit the equal of Vortec heads, much better than non-swirl-port heads of the same vintage). What I'm saying is that the swirlie heads actually have an excellent Intake/Exhaust flow ratio- around 75% or higher, even though the overall flow potential is not very high. An old school single pattern cam of mild duration, or a cam with only a mild split between intake and exhaust druation will actually work quite well for that reason. Like ~210* @ .050 would actually be pretty big compared to the stock cam (which is 191* @ .050 on the intake side) and will belt out low-midrange torque like nobody's business. No, it's not going to scream on the top end, but nothing can help those heads once the tach swings much past 4500-5000. So MATCH the cam to the RPM range the heads are capable of supporting and you can make bigtime torque in a usable RPM range.

And, like was said above, keep the LSA rather wide- 112* or wider. Makes tuning the stock system much easier, even with a custom tune.

Remember that the TBI computer system of that vintage is only 1 step up from the old computer controlled QJet systems of the early 80s. In short, they are slow and stupid. There is only so much you can do with them. Not a problem if you keep the combo relatively modest. But it ain't the EFI system you go racing with. A big lumpy cam, a MAP sensor (which isn't even used to build a real air density table in the ECM table) and a narrow band O2 sensor don't play nice together. They just can't deal very well with big cams unless you start turning off certain feedback features in the lower RPMs to "force" a drivable tune there.

AJ_72
05-18-2011, 01:24:58 AM
Well, let me know. I got it for free. Pay shipping and it's yours.

Pay it forward. ;)

GeauxTiger
05-18-2011, 05:58:46 AM
I'm very interested in how this turns out. I have a 95 Silverado TbI. 315k runs like a clock, but could use some new power in the future.

I'm not sure about the earlier trucks but the 95 is handcuffed by the computer. I love and hate that aspect but can't argue with the worry free service this of this vehicle....orig. owner planing to keep it.

Good luck with the cam swap!

woody80z28
05-18-2011, 08:02:57 AM
That sounds tough to pass up, AJ! Thanks!

I finally got my Beretta headers back last night and installed the drivetrain, but as soon as I have it running or the damn rain stops I'll check my truck to be sure it's a roller-ready block. Then I just need some lifters, etc.

docwilcar
05-18-2011, 07:56:14 PM
Take a look at the Isky 256/262 cam, 202-208-110 lsa. Isky designed this cam back in the 80's for a max torque 350 in a race car hauler. I have run this cam through the computer sim and it shows max hp of 259 at 4000 and max torque of 382 at 3000. I have talked to guys that have run this cam in their vehicles and they all said it was very smooth. I am looking to run this cam in my 84 TBI corvette and it pretty much blows away all the other mild rv type cams that I have run on the desk top dyno 5. The 206-212-112 comp you are looking at is very close to the Isky cam and the Comp 255 DEH 203-212-110 shows about the same numbers as the 206-212 cam. Hot rod did a cam test on the 255 DEH on a mild 8.8 c.r. 350 with RHS SR heads, 750 holley, headers and it made 17" of vacuum at 750 and 19" at 1000 and made 303 hp at 5000. I ran the Comp 252-206-206-110 cam in my 87 FB Formula with the stock 305 and it idled very smooth and I had the computer and electric quadrajet carb too. The 256262 makes more power and torque than the 252 cam. I am not afraid of 110 Lsa if the duration is kept fairly short and the 110 lsa usually will have better low end power than a 112-114 but will fall off quicker at higher rpm's. You can always call Ron Iskenderian and ask him about the 256/262 cam but I think it would work well in your combo!

woody80z28
05-19-2011, 02:39:44 PM
I looked up the LT1 cam and it has a little more lift and a little less duration than the Comp 249, and less I/E split which would be perfect for the swirl port heads.

I've done a lot of research on the 193 heads too, and while some say they are good for a truck at low RPM, the flow numbers don't lie...and Vortecs outflow them across the board except for exhaust at .100-.200 lift. And since I have a pair on the Camaro, it would be nice to throw some AFR's on the Camaro and the Vortecs on the truck.

My Camaro 355 is pretty well matched up now, but even so I think the AFR Eliminator 195's would be a nice upgrade over the Vortecs, and they'd give me room to grow in displacement & cam down the road. So for the price of AFR's I'd be upgrading two engines, not just one.

BondoSpecial
05-19-2011, 03:29:12 PM
woody if you were local I'd let you drive my TPI'd long bed with the LT1 roller cam and ported 083 heads, I think you'd like it, it is very strong. Vortec heads would be even better than what I used.

woody80z28
05-19-2011, 03:52:09 PM
083 or 193 heads? The TPI would be great for me, but I just dont have the time or ambition for that in my beater when I have so much else going on.

The flow numbers I saw stock vs stock 193s vs Vortecs was 165cfm vs 239 @ .500 intake and 140 vs 160 exhaust with similar splits all the way with intake and leveling off at about .300 for exhaust. It's awful tempting since I was thinking about buying an intake manifold anyway...

And some AFR's would be 270/207 at .500 for the Camaro, which would be great for my current single pattern cam.

BondoSpecial
05-19-2011, 03:57:44 PM
I used 083 heads. The engine and heads were from a 1989 Firebird GTA originally. I did bowl work and a 3 angle valve job on the heads @ home

woody80z28
05-20-2011, 08:54:25 AM
I did some playing around on desktop dyno last night and couldn't believe my eyes...I guess that's why it's a "simulation."

I added the flowbench numbers for the stock swirl ports and vortecs...and the swirl ports made more torque! I'm guessing DD assumes lower port flows mean more velocity, because the Vortec flow numbers are well above the 193s. It came up with like 408ftlbs for the 193s and 395 for the Vortecs. I've gotta call BS.

And in other news, does anyone know the IVO/IVC/EVO/EVC specs for the LT1 cam? I had to use the Comp 249 because I couldn't find the valve timing specs for the LT1, I just know the .050 duration, lift & lsa.

BondoSpecial
05-20-2011, 10:29:47 AM
I don't think you are gonna find that detailed info, I looked for it for the LT1 cam to do dynamic CR calcs but couldn't find it. Remember the Lt1 cam, the year I used at least (there are 2 different F body LT1 cams) is 117 LSA!!

77nomad
05-20-2011, 01:00:11 PM
I wish one of you guys lived in my neighborhood. I have a 91 extended cab long bed. Its big. Its stock but running like crap. I've changed egr, iac,tps,fuel pump,and map sensor. It still pops and stumbles. I'm thinking the cam is dying after 300,xxx miles. I,ve been told the bearings in the dizzy wear out on these too. I'm ready to pull the tbi and swap a carb and new cam just because I'm stumped.

BondoSpecial
05-20-2011, 01:02:51 PM
I have a bucket full of these small cap computer controlled HEI distributors and also a just-rebuilt TBI unit that I no longer use...if you were local you'd be welcome to swap this stuff on for some process of elimination testing. 300k miles is long in the tooth for anything though at that point you're fighting a losing battle!

Damon
05-20-2011, 10:02:23 PM
Nobody has good specs on the LT1 cam. The published .050 duration specs seem plausible, but the LSA and ICL (advance/retard) vary depending on whose specs you believe. Somewhere in the range of 115-117* LSA is often quoted and nobody argues with it. ICL (how advanced or retarded it is) is a different story. Many factory engines have timing chains with different TDC indexing than a common aftermarket chain set. The old engines seem to have chain sets that can be about 4* retarded from what an aftermarket chain would give you on the same cam. For instance, a factory-installed chain might drop you in right around 115-117* ICL (truly straight up) while an aftermarket chain set at 0* drops you in around 112* (~4* advanced). Pick your posion.

In short, getting true specs on a factory cam is a big 'ol mess. You pretty much have to accept that GM did a lot of work making them right for mild/stock motors and stop asking so many questions. Or break out the degree wheel and dial gague and measure for yourself.

Both the LT1 (F-body version only- not the Caprice version of the LT1) and the earlier TPI roller cams all decended from the old 305 L69 HO engine's flat tappet cam from the early 80s. The duration and LSA remained very close to those specs over the years despite the fact that they were turned into roller cams and put in EFI engines. Of course, the TPI (L98) cam had virtually identical lift to the old flat tappet cam (it was a roller cam clone of the original flat tappet design), while the LT1 cam had considerably more peak lift but still nearly identical duration and LSA. The succeeding engine families were each only mild incremental improvements over the previous engines in terms of cam design. It was a GOOD stock cam in 1982 (the first year for the L69 305 HO carbureted motor), just as good in 1992 (the last year for the TPI engine) and still good in 1997 (the last year for the LT1).

77nomad
05-21-2011, 05:04:56 AM
I have a bucket full of these small cap computer controlled HEI distributors and also a just-rebuilt TBI unit that I no longer use...if you were local you'd be welcome to swap this stuff on for some process of elimination testing. 300k miles is long in the tooth for anything though at that point you're fighting a losing battle!
Well I appreciate the what if offer. I did rebuild the TBI too. That was because a fuel line was loose and when I tightened it my gorilla grip snapped the housing. I had to go to a buiddies and mix and match until I had one that fit my motor. Rebuilt non the less. The only thing that worries me is the FP regulator may be the wrong pressure for my application. I have no idea where it came from or even if it matters. It ran fine afterward anyhow, it was a month later things began to get screwed up.:(
Again thanks.

retorq
05-21-2011, 01:07:22 PM
Well I appreciate the what if offer. I did rebuild the TBI too. That was because a fuel line was loose and when I tightened it my gorilla grip snapped the housing. I had to go to a buiddies and mix and match until I had one that fit my motor. Rebuilt non the less. The only thing that worries me is the FP regulator may be the wrong pressure for my application. I have no idea where it came from or even if it matters. It ran fine afterward anyhow, it was a month later things began to get screwed up.:(
Again thanks.

These engines are so picky about the fuel pressure. I used some double-jacketed fuel line from Jegs (push lock type) hose at the back of the TBI on both the feed and return lines and run a cheap Summit 0-30 fuel pressure gauge. You can mod your regulator to make it adjustable and set it where the computer expects it. Of course the injectors have to match what the computer thinks is there too ... I'm sure you can adjust the pressure to compensate but the stock pump will only put out so much fuel ...

77nomad
05-21-2011, 01:34:56 PM
Got a link to that mod?

AJ_72
05-21-2011, 02:08:58 PM
Damon,

I don't know how true it is, as far as specs, but do you remember Vader on www.thirdgen.org ?

He posted a chart showing the LT1 cam specs from different years, bodies, etc.

I'll have to see if I can find it. I saved it on my computer way back when, but I've been through about 5 computers since then. LOL

EDIT: Nevermind. I found it.

http://i114.photobucket.com/albums/n273/aj_danelle/LT1CamSpecs.gif

sooner
05-21-2011, 05:31:38 PM
This is ls1tech.com's version of the ltx cam specs

1992 Y-body: 205/207 0.451/0.450 lift 117 LSA
1993-1995 Y-body, F-body: 202/207 0.450/0.460 lift 116 LSA
1994-1996 B-bodies (including L99 4.3L): 191/196 0.418/0.430 lift 111 LSA
1996 Y-body, 1996-1997 F-body: 200/207 0.447/0.459 lift 117 LSA
1996 Y-body, F-body LT4: 203/210 0.476/0.479 lift 115 LSA

77nomad
05-22-2011, 12:33:49 AM
Every time you guys address Damon it take a second for me to realize your not talking to me. nomad=damon 77 is just when I was born. Anyhow carry on.

AJ_72
05-22-2011, 04:54:48 AM
LOL

I deal with that, too.

For the longest time, I was pretty much the only "AJ" here. Now there are a few floating around.

Plus my real name is Adam, and there are a couple of those, also.

sooner,

Those specs for the LT4 seem a little more realistic. 220* and 230* duration @ .050" seems highly unlikely for a stock EFI cam, even if it is limited prodution.

Hippie
05-22-2011, 07:57:54 PM
I did some playing around on desktop dyno last night and couldn't believe my eyes...I guess that's why it's a "simulation."

I added the flowbench numbers for the stock swirl ports and vortecs...and the swirl ports made more torque! I'm guessing DD assumes lower port flows mean more velocity, because the Vortec flow numbers are well above the 193s. It came up with like 408ftlbs for the 193s and 395 for the Vortecs. I've gotta call BS.


I've done the same comparison in DD2K with a 9.2 to 1 355 using several different mild cams such as the Vortec and Ramjet rollers and in mine the Swirl-Ports show more TQ from 2,000 - 3,000 in DD2K but from there on the Vortecs leave them in the dust which is exactly what people have reported in real life.

Huh, just realized I hadn't posted since joining 5-1/2 years ago........... Guess I didn't want to rush into anything.

woody80z28
05-23-2011, 09:28:51 AM
Congrats on popping your nasty cherry in my thread! haha

If that truly is the case, I'm fine with leaving the swirl ports on my truck. I don't need high-rpm power with my truck. Any of my hauling duties will be at a lower rpm anyway.

1972L
05-23-2011, 04:06:55 PM
For my 89 K1500/5.7/3.42's/700r4/ stock 265-75-16's
I went with the L98 5 speed roller
a liittle mild with 202*/207* @ .050"
and a low .430 lift.

I home ported the 193's
The shorty eBay headers mated to a Magneflow Y/ Jardine single 3"

Gets decent economy and makes decent torque.

Still need a tune (but that's on my list of 10,000 things to do)




http://i857.photobucket.com/albums/ab138/Billy-Biscayne/022.jpg

http://i857.photobucket.com/albums/ab138/Billy-Biscayne/006.jpg

http://i857.photobucket.com/albums/ab138/Billy-Biscayne/024.jpg

sooner
05-23-2011, 05:34:36 PM
I have a hard time believing that the swirl ports would make more torque than the vortecs.

The swirl ports use a 185cc intake port to deliver 178 cfm @.500 while the vortecs use a much smaller 170cc intake port to flow 230+cfm @ .500.

I dont know exactly what the cross section is on a swirl port head, but knowing that the port is much shorter than the vortec port, it is going to have way more cross section which is going to make for a dismally slow port velocity..I would venture to guess way under 100cfm/sq.in., while the vortec with its smaller port and much better flow will be above 130cfm/sq.in.

That being the case, I would think that the vortec would make gobs more torque based on the fact that it is filling the cylinders much much better at low rpm's because of its much better port velocity.

AJ_72
05-23-2011, 08:33:39 PM
I have a pair of 191 heads that measured out to 170 ccs.

77nomad
05-24-2011, 01:17:11 AM
Something very wrong sounding about popping a Nasty cherry.

woody80z28
05-24-2011, 09:12:42 AM
See, I assumed the Vortecs would be 100x better too, based on the great dyno-verified torque of any build I've ever read, and by the way they woke up my 355 in the Camaro (which to be fair was also over-cammed/under-compressed when I got it with the 882s.)

But it seems like there are 1 or 2 guys talking about how great the swirl ports are on the low end for every 2 or 3 guys slamming them as a garbage head (which for high-rpm power I'm sure they are.)

BondoSpecial
05-24-2011, 10:07:23 AM
Do you really think GM spent all that time and money on the vortec, which is a direct replacement for the 193, making a head that was in any way worse? Also do you see any 193 headed GMPP crate motors? Lol.

woody80z28
05-24-2011, 12:01:45 PM
I'm not doubting they're a better head. All I'm wondering is if it's worth the added cost for my application...

To go Vortec you're talking another intake ($400 to do it right, or maybe 200-50 for a carb intake with TBI adapter) and then the cost of the heads. I already have a pair and would like to upgrade the Camaro, so it would be foolish for me to buy another set (for the ~500 it would cost) but the AFR's for the Camaro are up to $1500 on their site.

1972L
05-24-2011, 03:23:47 PM
Do you really think GM spent all that time and money on the vortec, which is a direct replacement for the 193, making a head that was in any way worse? Also do you see any 193 headed GMPP crate motors? Lol.

Funny you should mention that
GM put swirl port heads on the LS9
No, not the 193 TBI heads
But they do have a wing like the TBI heads

Yes, they do sell it as a crate engine
http://www.race-mart.com/GM_Performance_Parts-GMP-19201990.html

Here's some info:
http://www.corvetteactioncenter.com/specs/c6/2009/zr1/ruthless_pursuit6.html

woody80z28
05-25-2011, 11:33:08 AM
Interesting they brought it back. Although here's an telltale tidbit:
While in a supercharged engine, these deflectors present virtually no restriction to air flow; in a normally aspirated application, they cause measurable power loss, so they are not present in the LS3/L92 casting.

Hippie
05-28-2011, 10:51:07 PM
Do you really think GM spent all that time and money on the vortec, which is a direct replacement for the 193, making a head that was in any way worse? Also do you see any 193 headed GMPP crate motors? Lol.

Depends on how you define "worse" I guess. Vortec heads were an adaptation of the LT-1 heads for truck use. GM spent the time and money on the LT-1 and fortunately for us it spilled over into trucks. I'm not arguing that it's a better "all around" head but it's not the one size fits all miracle some people think it is. There are some things it just doesn't do as well as other heads. There are some applications it just isn't right for and the Swirl Ports are. It's like Power Pak vs. Double Hump heads when I was a kid. Everybody "knew" Double Humps were better so they'd throw a set on their stock 283 Impala and then wonder why it went slower.

sooner
05-28-2011, 11:13:05 PM
I'm not arguing that it's a better "all around" head but it's not the one size fits all miracle some people think it is. There are some things it just doesn't do as well as other heads. There are some applications it just isn't right for and the Swirl Ports are.

^^Ok, Ill bite..explain an application that the swirl ports would be a better choice.

Hippie
05-29-2011, 10:52:46 AM
^^Ok, Ill bite..explain an application that the swirl ports would be a better choice.

I'm building a 355 for my C1500 and I started out intending to use L31 heads and the GMPP TBI intake but over the course of several months of researching cams, intakes, etc. I started finding people that had switched from Swirl Ports to Vortecs on mild builds in full size trucks and vans like I was planning and they reported that from an idle to 2500 they lost throttle response AND mileage but from there up it was a different story. The HP and TQ numbers above 2500 make using the Vortecs VERY tempting. However my goal on this particular build is primarily mileage and throttle response from an idle to 2000, that's where this truck spends 99% of it's time and I would be foolish to build it for the other 1%.

I realize that this is a very limited application but it is one where the Swirl Ports are the better choice. In fact I'm going so far as to use 305 Swirl Ports for a little extra mixture velocity. With 22cc D-cup pistons SCR will be about 9.15 to 1 and I'm shooting for a quench disatnce of .043" give or take a couple thousandths. I'm using the Vortec roller cam and stock TBI intake. My intake choice also goes against "conventional wisdom" but the factory dual plane is very hard to beat from an idle to 4,000, especially since I have 3 of them already. Peak TQ should occur about 2,000 or slightly lower and peak HP @ 4500.

Were I to step things up just a little with a little hotter cam and was after stronger mid-range acceleration with bottom end being secondary I'd go for the Vortecs. It's not that they have "bad" low end but I want that extra the Swirl Ports have to offer. Most people don't "get" what I'm building and that's OK. I'm not building it for them.;)

retorq
05-29-2011, 01:10:27 PM
Got a link to that mod?

http://www.thirdgen.org/tbi-afpr

woody80z28
05-31-2011, 03:14:33 PM
I'm building a 355 for my C1500 and I started out intending to use L31 heads and the GMPP TBI intake but over the course of several months of researching cams, intakes, etc. I started finding people that had switched from Swirl Ports to Vortecs on mild builds in full size trucks and vans like I was planning and they reported that from an idle to 2500 they lost throttle response AND mileage but from there up it was a different story. The HP and TQ numbers above 2500 make using the Vortecs VERY tempting. However my goal on this particular build is primarily mileage and throttle response from an idle to 2000, that's where this truck spends 99% of it's time and I would be foolish to build it for the other 1%.

I realize that this is a very limited application but it is one where the Swirl Ports are the better choice. In fact I'm going so far as to use 305 Swirl Ports for a little extra mixture velocity. With 22cc D-cup pistons SCR will be about 9.15 to 1 and I'm shooting for a quench disatnce of .043" give or take a couple thousandths. I'm using the Vortec roller cam and stock TBI intake. My intake choice also goes against "conventional wisdom" but the factory dual plane is very hard to beat from an idle to 4,000, especially since I have 3 of them already. Peak TQ should occur about 2,000 or slightly lower and peak HP @ 4500.

Were I to step things up just a little with a little hotter cam and was after stronger mid-range acceleration with bottom end being secondary I'd go for the Vortecs. It's not that they have "bad" low end but I want that extra the Swirl Ports have to offer. Most people don't "get" what I'm building and that's OK. I'm not building it for them.;)

I made a thread on the FSC forum to get some background on the subject and I get answers from both sides...some say the SPs perfect for a truck at low RPM and better than Vortecs under 3000, some say the Vortecs are equal at low end and far superior top end...

I wish someone had dyno numbers to back up either side. haha

http://www.fullsizechevy.com/forum/general-discussion/performance/474906-truth-about-vortecs-vs-stock-swirl-ports-truck.html

BondoSpecial
05-31-2011, 03:17:34 PM
You mean you're not done yet? You coulda done a TPI conversion already!! I am chirping the 1-2 shift with my stock 254,000 mile 700R and you are still thinkin about heads!

Just kidding

woody80z28
05-31-2011, 03:25:56 PM
You mean you're not done yet? You coulda done a TPI conversion already!! I am chirping the 1-2 shift with my stock 254,000 mile 700R and you are still thinkin about heads!

Just kidding
hahaha

It's still in the back yard untouched. Now that the Beretta is out of the garage I can get into it...as soon as I get back from a work trip on Friday.

I also like to do my homework and make sure I'm making the best decision.

BondoSpecial
05-31-2011, 03:33:00 PM
there is no such thing as a "best" option when TBI is involved.

Are you going to be at the camaro nationals? If you're going maybe I can drive TPI truckster and let you drive it and see what you think of my creation. At least it has the LT1 cam in it for reference for how it runs/sounds. It really gets your attention when you dump down a gear in this heavy POS and there is actually quite a bit of power there (it will chirp the 265/70s on a downshift at lower speeds, its pretty funny).

woody80z28
05-31-2011, 03:44:56 PM
I'm hoping to have the truck done by Camaro Nat'ls since I need to use it to do the roof on my house! haha

Crunch time is another reason it would be nice to go with the SP's since Vortecs would mean tearing apart the Camaro too in my little 2-car garage. And we all know how much more room vehicles take up when unassembled...

BondoSpecial
05-31-2011, 03:48:36 PM
judging by how smooth the LT1 cam idles (i am idling it at 600 rpms w/ AC on and everything and it is smoooooth) I don't think you'd have any regrets even if you put that cam in with 193s and TBI. Then bring your finished product to the nationals and we'll have a truck duel.

77nomad
05-31-2011, 08:01:01 PM
http://www.thirdgen.org/tbi-afpr
TY bookmarked for future reference.

Damon
05-31-2011, 08:21:18 PM
I'm pretty sure I understood where you were going with this build which is why I didn't divert down the Vortec road with my suggestions. So let me make a few more observations since this thread has thrown a lot of ideas up on the table since my original reply.....

DON'T use the 305 swirlies. The ports are identical, only the intake valve is smaller (1.94 vs. 1.84) and the chambers as well. Because of their design the swirlie intakes act much SMALLER than their actual volume (which is around 185cc, believe it or not). Half the intake port is blocked off behind the intake valve and gradually tapers up to form a ramp on the other side- that's how they get so much swirl in the mixture. The bigger intake valve will NOT cost you any torque and the overall flow potential is greater. Don't choke a 350 cube motor any further than your existing heads already do for no reason.

PLUS YOU ALREADY OWN THEM!

If you want to get fancy you can get a performance valve job plus some mild pocket porting and make those heads flow better than stock non-swirlies (you won't ever get them to Vortec flow levels, though, except on the exhaust side, without serious work). I wouldn't recommend it becuase it's a mod nobody will ever pay you for if you resell them, but it can extract quite a bit more power from those supposedly "junk" swirlies.

Another suggestion.... bump up the compression ratio on the motor. Stock pistons are dished in your LO5. Swap to flattops with your existing heads (which have 64cc chambers) and you get compression up around 10:1 PLUS better quench. COMPRESSION ALWAYS BUILDS TORQUE. Especially in the super-down-low RPMs.

A 2-hole spacer between the TB and the (stock) intake is always a torque-adder on a TBI engine. Never heard of one losing power. Only a matter of how much it adds.

And, of course, my previous cam suggestions still apply.

Whatever you do, get it TUNED when you're done. The stock tuning sucks even on a stock engine. Make any modifications and it gets even further away from optimal. This is one area where GM left a LOT on the table, even on a stock engine. On a modified one it's just silly trying to make a stock tune run it- it will be way off, guaranteed.

You might not hit more than 250 peak HP (at the flywheel, even with a decent flowing exhaust), but the torque curve will be mountainous starting right off idle. It will GO a lot better than the peak power numbers would suggest. Usable, right-now kinda power. Steep gears and high stall converters need not apply.

woody80z28
06-01-2011, 09:35:11 AM
Hi Damon, thanks for the reply! It sounds like you have some experience working with these heads.

I was thinking about bumping compression with a simple .015 head gasket like I did with the Camaro (assuming the quench will be right, I dont know how far the pistons are in the hole...or if there is even enough flat surface with the dish to make it work). I will know better once I get the heads off and see. I just checked Summit and see they have cheapo flat tops for $100, but getting the quench right should put me over 10:1 and I don't want to run 93 in my beater.

I do have a 2-hole 1" spacer that I modified to suck air from both TB bores, and I've also heard the stock intake isn't bad unless you're running more RPMs too. I did do the "Ultimate TBI" stuff when I first bought the truck (thinned throttle plate bars, smoothed bores, injector pod spacer...)

I have an Autoprom that I've been tuning my Beretta with that I can use to burn chips for the truck. I think when I put the headers on I'll add another o2 bung for my wideband.

Which way is the tune in stock form? I've datalogged it before and saw the ECM was removing some fuel (BLMs around 120) and the FSC guys say they like more timing.

Damon
06-01-2011, 08:29:16 PM
Tuning is, unfortunately, all over the place.

The spark curves are weak and can use some beefing up, but like Vortec heads, they don't need tons of total advance (~32* @ WOT above 3000 RPMs). Par throttle spark advance can likewise be brought in much more aggressively than the stock chip. They seemed to keep the advance curves modest to help emissions, but hurting performance. In some cases, using a different base timing setting (like 6-10* initial instead of the stock 0* setting) helps get you closer without dialing in giant gobs of timing advance in the chip programming. (Quite frankly, advancing the timing 4-6* over stock often helps on even a dead-stock motor with stock tuning!)

They can run rich or lean at different throttle positions and RPMs- it doesn't seem to line up with an easily understood trend line. I'm NOT a pro at tuning these FI systems, so I'm just going by what my brother has told me in his tuning efforts and general observation of some of the sharp cookies over on Thirdgen.org.

You would think that everything would run lean on a modified motor and it can and often does at WOT, but part throttle is just all over the map depending on the exact modifications.

What I'm saying is that there is no "general direction" to go with the fuel maps. If it's lean in one spot and rich in another you can't fix it by moving the whole fuel curve up or down. You MUST tune the bumps and dips out of it when and where needed.

The wideband O2 is a really good idea if you're going to tackle that, I agree.

One little tuning trick to keep in the back of your mind on GM TBI systems..... if you get to the point you need "bigger injectors" to feed the motor at WOT.... you usually don't need them. Stock TBI systems run at about 12 PSI at the pods. But they were engineered to run at MUCH higher pressures without any problems. You can easily run stock TBI injectors at 2X or even 3X the stock fuel pressure witout any worry of overpowering the electromagnets that open the injector pintles. In other words, you can basically make the injectors twice as big just by changing the fuel pressure, if you need to. Of course, you need a high rpessure fuel pump (like from a TPI engine because the stock TBI pump poops out around 15 PSI) as well as an adjustable fuel pressure regulator (becuase the stock regulator is built into the TB itself). And lots of guys use a vacuum-adjustable fuel pressure regulator when they do this mod so pressure is lower at light throttle but kicks up to the higher pressure when you put the pedal to the carpet. They're really kinda cool systems when you spend the time to tune them- like a carb with infinite tunability. But they're still power-limited just because of their flow and the limitations of the injectors and intake manifold. Below ~300HP the tunability far outweighs the inherent limitations. Also awesome if you want to go hardcore off-roading where the vehicle can see some extreme angles- no way to tune around that kinds stuff with a carb. Fuel injectoion won't even blink at that, even if the engine is totally upside down!

1972L
06-01-2011, 10:17:21 PM
As a Vortec vs Swirl port comparison I can offer this

In 2000 I bought a new Tahoe Limited with the L31 5.7
I still have it with 65,000 miles on the clock
100% OEM down to the AC Delco air filter and battery (replacements of course, but all GM, No mods, the only thing on the truck on the truck is a non OEM IAC valve that was replaced in a pinch one late Sunday afternoon) Tires are non OEM, the OEM was 255/70/16, I have 265/70/16's on it now.

The L31 was rated 255hp/ 330tq@ 2800 rpm

My 89 K1500 K code LO5 was rated 300tq @ 2800 rpm

Of course the L31 has better heads, roller oem cam and better injection/induction. The LO5 had crappy swirl port heads and an anemic induction/exhaust system and a flat tappet cam with much less lift and duration.

Both trucks have 3.42's
The K1500 has 265/75/16's
same auto tranny ratios in both trucks
The k1500 does sit a few inches higher than the Tahoe

With the ported 193's/L98 cam and a set of headers the K1500 will tow a 3000lb load in OD with ease. The L31 has a harder time with it. (same boat for the last 10 years).

I built the LO5 as a truck motor
Low end grunt and decent fuel economy
With gas @ $4.00 a gallon it hasn't seen over 3500 rpm in at least a week.

Just my $.02
Take it for what's it's worth.

woody80z28
06-06-2011, 11:08:35 AM
I guess I've got to do some homework on the correct way to port some 193s.

woody80z28
06-10-2011, 07:30:51 AM
Finally got it in the garage last night to start the teardown. Did a compression test and got 120, 120, 125, 125, 130, 130, 130, 135. Seems a little low to me, but it's fairly consistent.

woody80z28
06-14-2011, 10:27:01 PM
Turns out I don't have 193 heads, whoever built the engine used #187 305 swirlies. No wonder it's a goddam slug! The pistons also have a huge dish...they're H580P .040s, which according to google are either 16 or 22cc dish. That puts my compression at maybe 9:1 even with the 58cc 305 heads.

The good news is the block is roller ready, and the cylinder bores look good and there's no sludge or anything. It's only a 2-bolt main, but that's fine for my usage. I did double check the block once I saw the heads and it is a 350.

So I'm thinking...LT1 roller cam, some much smaller dish pistons and Vortecs since I need heads anyway. That also means a new intake, so I'm open to suggestions.

http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4df5f478c9769/tn_full_IMG_6284JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4df5f48ecea84/tn_full_IMG_6289JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4df815fa4b8c7/tn_full_IMG_6296JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4df816079464c/tn_full_IMG_6297JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4df8160dc3864/tn_full_IMG_6299JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4df81618d0a79/tn_full_IMG_6302JPG_Thumbnail1.jpg
Here's the scrap metal pile!
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4df8162396680/tn_full_IMG_6305JPG_Thumbnail1.jpg

woody80z28
06-15-2011, 10:45:34 AM
I found some 10cc pistons on Summit that look like they have a decent quench area. Assuming I can get a gasket to match my deck clearance for .040 quench they will get me to 9.86:1. I think I can get away with that with the Vortec chamber. For a heavy load like towing the Camaro I'd run 93, but I think 89 would be good for most driving.

http://www.summitracing.com/parts/SLP-H423ACP40/

As for intake shopping I can get a Weiand from AJ that would probably work. It has no EGR, but I did some homework and I can't run an EGR with Vortecs anyway.

BondoSpecial
06-15-2011, 10:53:43 AM
why can't we run EGR with vortecs? I am workin on a vortec headed engine build and although none of my old stuff needs to pass emissions, lately I have been putting egr and cats on just to keep it clean (my allergies appreciate it too). I just assumed I could also run EGR w/ the vortecs but didn't really think much about it yet.

woody80z28
06-15-2011, 11:29:31 AM
The TBI exhaust gas comes through the head to the intake. You can do it with Vortec heads, but you have to add an EGR pipe from the header to plumb to the intake. And then you have to use the hella-expensive GMPP TBI intake to get the EGR mounted.

BondoSpecial
06-15-2011, 11:58:53 AM
oh. Thanks for the info. It's not a big deal, EFI + cat is still plenty clean running compared to carbs & no cat. I did not realize that was gonna be the case though w/ EGR. I am adapting a TPI base to Vortec heads for the iroc build (requires welding)

woody80z28
06-15-2011, 01:32:13 PM
I'm not sure how the TPI EGR works, you might need a tube anyway...that's how my Beretta was.

BondoSpecial
06-15-2011, 01:49:29 PM
TPI EGR is like any other Gen 1 style setup, through the crossover and into a manifold-base mounted valve.

boogie
06-15-2011, 05:27:23 PM
I would run the GMPP Ram jet cam in that over the LT1. I have ran both in TBI trucks and liked the Ram jet better.

Damon
06-15-2011, 10:38:48 PM
GMPP makes a intake that puts a TBI system onto Vortec heads (bolt-on, no adapter). The EGR would still have to be plumbed in externally to make it functional. But given the heads-and-cam upgrade you're doing, you're going to be into the chip programming anyway. Might as well just turn the EGR valve off in the chip while you're in there tuning and save a lot of plumbing hassle. You can still leave it physically installed if you want, it just won't be functional if you turn it off in the chip (EGR solenoid will remain at 0% duty cycle under all conditions).

The RamJet cam is very similar to the stock Vortec truck engine cam, but with more lift. It would work fine, but so would a lot of other stock and near-stock roller cams. Certainly, if brutal low end torque is your goal, the RamJet cam wou8ld probably give that to you in spades (and it's still a bit more aggressive than the stock TBI cam). You can go a little hotter if you want- I wouldn't shy away from it, within reason.

Vortec heads with flattops (-6cc dish) will get you around to 10:1 compression on a 350, depending on deck height and head gasket. If you want to back it down a little, go with slightly dished pistons. Even commonly available -12cc dish aftermarket pistons will get you in the mid 9s, which is a good match for the combo, especially if running on less than pump premium gas.

Just beware of cheap "rebuilder" pistons that have a lower pin height. They can drop the piston too far in the hole on an undecked block, killing compression and quench. You want performance-oriented aftermarket pistons that will keep the piston around .025" from the top of the deck at TDC, even on an undecked block.

woody80z28
06-16-2011, 08:45:01 AM
Those sealed power pistons I posted should be ok, shouldn't they? I know the flat tops in my Camaro were .024" in the hole and I'm expecting the truck to be about the same. So a .015 gasket with those SP 10cc pistons should get me to 9.8:1.

I'm getting a used LT1 cam from AJ, and he also has a carb Vortec Performer for cheap...so I can just delete the EGR and get an adapter plate for the TBI. My brother-in-law is supposed to be getting a rod-knock Vortec long block in trade this week that I'm gonna buy for a few hundred bucks that will have the heads and all the roller lifters, spider, etc that I need.

I'm hoping I can get close to 100ftlb for under $1000. And I'm sure hp would be much better too - considering it was a maybe 9:1 stock cam 350 with 305 heads choking it off.

Hippie
06-16-2011, 09:10:07 PM
The cranking compression you posted is low even for a 9 to 1 engine. My old '76 Monte Carlo with the bone stock 90,000 mile 8.5 to 1 350 would crank at 175-180. Whoever built your engine cheaped out and killed what could have potentially been a decent daily driver engine. The H580P's have a 22cc full dish and a deck height of .036. What did it have for head gaskets? I'm guessing probably a std. Fel-Pro Permatorque with a compressed thickness of .040". With a .015" steel shim head gasket you would have 9.0 to 1 at best and no quench whatsoever. A bad combination and even worse with a thicker head gasket. I assume it still had the TBI "Peanut" cam in it too?

woody80z28
06-16-2011, 10:07:30 PM
The cranking compression you posted is low even for a 9 to 1 engine. My old '76 Monte Carlo with the bone stock 90,000 mile 8.5 to 1 350 would crank at 175-180. Whoever built your engine cheaped out and killed what could have potentially been a decent daily driver engine. The H580P's have a 22cc full dish and a deck height of .036. What did it have for head gaskets? I'm guessing probably a std. Fel-Pro Permatorque with a compressed thickness of .040". With a .015" steel shim head gasket you would have 9.0 to 1 at best and no quench whatsoever. A bad combination and even worse with a thicker head gasket. I assume it still had the TBI "Peanut" cam in it too?

I'm assuming the cam was stock TBI...it was gutless. I checked the deck height tonight at it read .032 on one side of the piston and .025 on the other, which is weird. Didnt measure the head gaskets, but they're pretty thick so I'm guessing .040ish. So I'm gonna buy those Sealed Power 10cc's and see what they have for deck clearance before ordering a head gasket. With Vortecs you get lots of area for quench so it should be pretty detonation-resistant.

Damon
06-17-2011, 08:35:02 AM
Go look at the piston pin height on a bunch of cheap 350 pistons for 5.7" rods on Summit's website. You will see 2 different numbers pop up over and over again. The higher number is less in the hole (piston face closer to deck height when installed). The ones with the lower pin height number sit further in the hole and are usually cheaper "rebuilder" pistons.

woody80z28
06-17-2011, 10:42:55 AM
Go look at the piston pin height on a bunch of cheap 350 pistons for 5.7" rods on Summit's website. You will see 2 different numbers pop up over and over again. The higher number is less in the hole (piston face closer to deck height when installed). The ones with the lower pin height number sit further in the hole and are usually cheaper "rebuilder" pistons.

Is the compression distance the pin height spec you're talking about? I'm guessing it is, and that's bad news cause the Sealed Powers I was looking at are 1.540 and most of the more expensive pistons are around 1.560.

I just checked the PN and the pistons in it now are also 1.540, which should mean those 10cc'ers would have the same deck clearance which was .025-.032. I'll double check that spec on a few different cylinders tonight though.

BondoSpecial
06-17-2011, 10:48:45 AM
I disagree about his compression #s in the 120's being low, they seem normal to me. My 083 headed 30 over 350 with under 10% measured leak down cranks in the 120's as well @ 9:1 compression (although this was admittedly with a battery that had seen better days and with a gear reduction starter that does not turn the engine over all that fast, a 1:1 starter and a fresh batt may have made a diff in my case)

But I wouldn't sweat those comp #s. Cam and cranking speed will make a big difference in what one person sees vs another with similar engines

woody80z28
06-17-2011, 11:54:51 AM
I disagree about his compression #s in the 120's being low, they seem normal to me. My 083 headed 30 over 350 with under 10% measured leak down cranks in the 120's as well @ 9:1 compression (although this was admittedly with a battery that had seen better days and with a gear reduction starter that does not turn the engine over all that fast, a 1:1 starter and a fresh batt may have made a diff in my case)

But I wouldn't sweat those comp #s. Cam and cranking speed will make a big difference in what one person sees vs another with similar engines
I thought the gear reduction starters I put on my Camaro and Beretta cranked quicker than the full size ones? And my truck has the factory gear reduction unit.

With a true 22cc dish and the pistons appx .029 in the hole and a .039 head gaskets it puts compression at 8.76:1 with the 58cc 305 heads according to Summit's calculator. If I go by the .036+.040 hippie posted then it is 8.62:1. I do know it was a slug.

I think the moral of the story is...a little more cam with another point compression and vortecs vs 305 swirlies it should run a lot better now.

BondoSpecial
06-17-2011, 12:32:27 PM
"reduction" to me meant slower...I figured that's how they get away with using the tiny little motor on there. My truck sure sounds like it cranks with fewer rpms w/ the mini starter than it did with the big Remy one but maybe I'm wrong, I dunno. Whatever the case the battery I was using to get those #s on the dish top/ 64cc head 350 w/ the LT1 cam was on its way out so cranking speed could have been higher.

AJ_72
06-17-2011, 04:00:37 PM
These pistons would work well.

http://www.summitracing.com/parts/SUM-17350-40/

Flat tops with Vortecs will put you right around the 10:1 compression ratio of the LT1. Should work well with that cam.

And they're cheap, too. ;)

woody80z28
06-17-2011, 08:32:11 PM
I figured those up and with the right quench it would be 10.3:1, which would be too much compression. I think 9.8 would be better for a heavy truck.

BondoSpecial
06-17-2011, 10:16:45 PM
9.8, 10.3, splitting hairs at that point, they are both a lot of compression for something used for towing I would think, a small dish might be a better idea. What CR did vortec trucks have from the factory?

AJ_72
06-17-2011, 10:57:57 PM
I figured those up and with the right quench it would be 10.3:1, which would be too much compression. I think 9.8 would be better for a heavy truck.

10.3 would be better with the right quench distance than 9.8 with the wrong quench distance. ;)

The L31 engine had a compression ratio of 9.4:1 in 1996.

http://archives.media.gm.com/division/chevrolet/products/archive_prod_info/pguide/ckpickup/ckpspec2.htm

But here's the thing to keep in mind.

The LT1 cam was designed with a 10.4:1 compression. Granted, they used aluminum heads and reverse flow cooling, but if you drop it much lower than 10.4:1, you'll have less cylinder pressure because of the increased duration.

From what I found, here's the cam on the Vortec L31
@.050" 191/196 0.414"/.428" lift on a 111 LSA.

Here are all the possible LT1 cams.

1992 Y-body: 205/207 0.451/0.450 lift 117 LSA
1993-1995 Y-body, F-body: 202/207 0.450/0.460 lift 116 LSA
1994-1996 B-bodies (including L99 4.3L): 191/196 0.418/0.430 lift 111 LSA
1996 Y-body, 1996-1997 F-body: 200/207 0.447/0.459 lift 117 LSA
1996 Y-body, F-body LT4: 203/210 0.476/0.479 lift 115 LSA

My cam may be any one of those, but notice the bold one? It's nearly identical to the Vortec L31 specs, and the compression ratio didn't change in the B-bodies, which had iron heads. Plus, the B-bodies are heavy cars that also came with a tow package.

IMO, it'd be fine with 91+ octane.

On the flip side, it's better to be safe than sorry. I just looked for pistons that were cheap, and would work for you with the right compression height (1.56")

BondoSpecial
06-18-2011, 12:19:11 AM
The LT1 cam was designed with a 10.4:1 compression.

You're forgetting something...10.4:1 compression with ALUMINUM HEADS. I am running the LT1 cam with 9:1 compression with EFI and iron heads in a 5200 lb truck and it is not lacking and likes 87 octane. I'd rather have too little compression than too much in a work vehicle. Just a thought, because if you have too much compression and it either requires premium fuel or needs a lot of timing pulled, the compression has done you no favors.

I guess the point is keeping it under 10:1 is probably a good idea.

AJ_72
06-18-2011, 01:04:38 AM
I didn't forget anything.

I said "granted, they used aluminum heads and reverse flow cooling".

I proceeded to say "compression ratio didn't change in the B-bodies, which had iron heads".

Fuel injection with timing tables and a knock sensor is a wonderful thing.

He can do whatever he likes. I'm just explaining to him what his options are, and to realize the days of "you can't run more than 10 to 1 compression on pump gas" are gone.

BondoSpecial
06-18-2011, 01:06:04 AM
damn I must be tired. stepping away from the message board.....

AJ_72
06-18-2011, 01:52:49 AM
LOL

No harm, no foul. I'm a night owl since I've been working 2nd shift since December. ;)

Another thing to remember is Vortec heads require less timing because of their chamber design. So I don't think pulling back the timing would be a bad thing, anyway.

I'll do Woody a favor and search for a slightly dished piston in the same price range. I can't argue that going with less compression (~9.5) would probably work better for his application. I just don't think higher compression would hurt either.

Hippie
06-18-2011, 09:13:24 AM
With Vortecs you get lots of area for quench so it should be pretty detonation-resistant.

It's not the quench area on the head you have to worry about, it's the piston. Any dished piston you use will have to have a D-cup or "reverse dome" and a minimum of a 1.560 pin height to have any quench affect.

L-31 Vortecs have better detonation resistance than other SBC heads because of the swirl affect from the heart shaped chamber combined with the 350's 4" bore. It's my understanding GM made the L30 305 Vortec heads a "mini-Swirl Port" with the small ramp in the intake port and regular shaped chambers instead because the 305's small bore negated any of the swirl affect from the heart shape chamber.

I stand by my statement that 120 PSI is low for a 9 to 1 SBC, especially one with the short duration Peanut cam. It may be "functional" but certainly not normal in my book. I've owned literally dozens of SBC's over the years from 283's to 400's. None of them that weren't coughing up a lung were ever under 135 and those were the 70's era Smog Dogs with 76cc heads, crappy cams and retarded timing. 30 some years ago I stuck a Crane HT-284 cam in an otherwise stock '78 truck 350 4 bbl. that was "maybe" 8.0 to 1 stock and even it still cranked at 140. It was also gutless until 3,000 RPM, live and learn.........:screwup:

FWIW, I'm doing all future builds that I plan on keeping on the premise that in the near future 87 Octane is going to be the "good" stuff........... a rumor I heard from someone in the industry.

woody80z28
06-18-2011, 10:31:39 AM
All my numbers have been figured with .040 quench, because I know it's important. I'm not afraid of compression, I know it is good for power and efficiency both...the Camaro is 10.55:1 with vortecs and a carb with no knock sensor and I've never had any detonation issues. But we're talking a 3300lb vehicle with more cam and a manual trans...not a more conservative cam in a 4500lb auto that should be able to tow 5000lbs, and I'd like to run my winter beater on 87 or 89 rather than my summer toy on 93.

Those sealed power pistons have a decent amount of quench area because the small 10cc dish is in the center of the piston. The pin height is the only thing that could be bad. I never got a chance to measure the other pistons last night to see what they all would be. If the block was decked when rebuilt the compression height distance might not be bad.

Hippie
06-18-2011, 02:31:19 PM
Those sealed power pistons have a decent amount of quench area because the small 10cc dish is in the center of the piston.


Personally I have doubts about how well those would work for proper quench. They're cut away at the center of the quench area. If just a few thousandths on the distance makes such a big difference I'm thinking a big void right in the middle can't help. I think you'd be better off with something like these:

http://www.kb-silvolite.com/images/piston/LKB118.gif

But they're almost twice as much and it's your money not mine. The KB118's pictured are what I just bought for my build. I would have posted the actual pic but it filled my whole 17" monitor when I did the preview.

woody80z28
06-18-2011, 08:00:23 PM
Those KB ones really do match up well with the quench area of the Vortec chamber.

I definitely want the engine to run on 87 or 89 regularly, so I can run 93 as a little added protection with a heavy load like hauling a heavy trailer. Stock 1/2 tons were 9.25:1 and 3/4 & 1 tons were 8.75:1 for just that reason.

1972L
06-18-2011, 09:02:25 PM
Is the compression distance the pin height spec you're talking about? I'm guessing it is, and that's bad news cause the Sealed Powers I was looking at are 1.540 and most of the more expensive pistons are around 1.560.

I just checked the PN and the pistons in it now are also 1.540, which should mean those 10cc'ers would have the same deck clearance which was .025-.032. I'll double check that spec on a few different cylinders tonight though.

I used Sealed Power H345NP
1.560 comp height
5/64 rings
5 cc

http://www.jegs.com/i/Sealed%20Power/844/345NP/10002/-1?CT=999

the set I used was made in the USA
I heard that they have been offshored
Ask before you buy

Hippie
06-18-2011, 10:57:53 PM
I heard that they have been offshored
Ask before you buy

You heard correctly, I just recently bought a set of Speed Pro flat top Hypers for a 305 and on the box it said "Made in India". My KB's were "Hecho en Mexico". I bought new GM AC lines for my car and when I pulled them out of the GM box there was a big tag wrapped around the line that said "Made in China". It's getting harder and harder to find "Made in the USA" and even when you do it's no guarantee it's any good. :(

AJ_72
06-19-2011, 01:46:32 AM
I'm confused why you need new pistons.

Using this online calculator, using .032" below deck height, Fel-Pro .015" thick gaskets and 22cc dish pistons, I come up with 8.5:1 compression ratio.
http://www.csgnetwork.com/compcalc.html

That's worse case scenario. If the dish in the piston is only 16cc, you're looking at 8.9:1, worse case scenario.

Using the LT1 cam, I used DD2003 and running the worst flow numbers I have for Vortec heads , stock manifolds w/mufflers, 8.5:1 compression, and the LT1 cam, the least amount of HP you'll make is ~255 @ 5,000 RPM, and ~350 lb/ft of torque @ 3,000 RPM.

Going through the trouble to change the pistons to attain 9.5:1 compression ratio is worth 270 HP @ 5,000 RPM and 366 lb/ft @ 3,000 RPM.
Is 15 HP and 16 lb/ft of torque worth the hassle?

A set of headers and free flowing exhaust (if you don't already have them) is probably worth more of a gain in HP and TQ than changing pistons.

Hippie
06-19-2011, 07:29:22 AM
I'm confused why you need new pistons.

Using this online calculator, using .032" below deck height, Fel-Pro .015" thick gaskets and 22cc dish pistons, I come up with 8.5:1 compression ratio.
http://www.csgnetwork.com/compcalc.html

That's worse case scenario. If the dish in the piston is only 16cc, you're looking at 8.9:1, worse case scenario.

A set of headers and free flowing exhaust (if you don't already have them) is probably worth more of a gain in HP and TQ than changing pistons.

Woody has done his homework and he's on the right track. The H580Ps are low buck cast pistons and have a full dish, they look more like ash trays than pistons. They are intended for rebuilders who want to use 305 heads on a 350 while keeping the compression down around 9 to 1. Great for building a cheap DD engine out of what you have laying around and not much else. You can't get any quench with them at all which is critical to torque production and detonation resistance. Quench can make or break an engine, he stands to gain more from the quench than just what the difference in gompression will make. The two combined make it worth spending the extra bucks.

I have a set I bought to do just that and could have saved myself about $300 by using them for my truck 350 instead of the KB118's I just bought but I would have had no quench whatsoever.

BTW guys, as of last night I have abandoned the '187 heads and Vortec cam for my build. I found a "deal" on a set of Doug Thorley TriY headers for a Vortec 350 that have the correct bungs for the EGR tube and O2 sensor. My original plan was to use L30 Vortec heads with the GMPP Vortec TBI intake and '395 Ramjet roller cam but for various reasons things got downgraded a little. Partly because I had been going to keep the 2.73 gears and needed as much TQ below 3,000 as I could get out of the 350 I am building. I started hearing bad noises from the diff right after having the 700R4 rebuilt and the shifts firmed up a "bit" so the truck is in the shop as I write getting a 3.73 posi and that changes things a bit. I could have just as easily used L31 Vortecs but I still want to keep my TQ band a little lower than what it would be with the L-31's. Most people don't understand why but I have my reasons.....

I compared this combo to my old 383 in DD2000. I won't post any numbers because, they'd just be that, a bunch of numbers. Knowing what my 383 actually ran like though and comparing the TQ and HP curves........... I'm pretty excited to get this thing together.:happy:

AJ_72
06-19-2011, 06:39:32 PM
But if he kept the compression around 8.5:1 to 9:1 he wouldn't need to worry about quench. Detonation would be virtually nonexistent with fuel injection.

Plus, it's a budget build.

Again, I'm just giving him options, not trying to tell him what to do.

Hippie
06-19-2011, 08:39:29 PM
But if he kept the compression around 8.5:1 to 9:1 he wouldn't need to worry about quench. Detonation would be virtually nonexistent with fuel injection.


Please don't think I'm trying to be a know it all, far from it, in fact I thought the same thing once upon a time. I've been doing lots of research on a very similar build for a C1500 and I'm not just parroting what I've read on the internet. This is NOT my first engine by a long shot and I've made the same mistakes I'm talking about. Boy, have I! :eek: I've learned from those mistakes and I'm still learning. Having proper quench even on a budget build is one of the more expensive lessons I learned, it makes a difference. It's up to Woody on what he does and I too am trying to give him options based on my experiences and research and the experiences of my friends and associates which spans several decades. I tore into my first SBC 39 years ago this month. I've built some good running street engines and I've built some dismal failures. One of my "successes" was the 383 I mentioned. I built it in 1982, had I known then what I know now it could have been SO much more! We thought it was really something, by today's standards it was wrong from top to bottom but it still worked pretty darn good.


An 8.5 to 1 engine with a short duration cam and no quench is far more likely to detonate than an otherwise identical engine with 9.5 to 1 and proper quench and just because you can't hear it doesn't mean an engine isn't detonating. A TBI engine most certainly CAN detonate when under a heavy load on a hot day. True it's less likely to than a carbed engine but I've had them do it. The ECM has it's limits and when it's pulling back the timing to try to stop the detonation you're giving up power and fuel economy. There's extra power to be had from running a tight quench, especially on the low end where a truck needs it. I understand it's a budget build but the extra bucks for the right pistons will pay off.

It's always cheaper to do it right than do it over.

woody80z28
06-19-2011, 09:36:16 PM
It's always cheaper to do it right than do it over.
That is true. I have thought about this for about 5 years now after building my Camaro 355...I left some power on the table by leaving in the flat tappet cam and going with Vortecs rather than AFRs. So now I'm itching to build that rod-knock Vortec long block as a forged 383 with AFRs and a roller with EFI, so I can get the street throttle response I had with my 600 carb and the top end of the 750, but with another 75-100hp on tap.

Looking at the pistons in my truck engine now and how easy it is to swap them at this point it's worth it to me. I don't like to downgrade anything, and that's what I'd be doing at less than 9:1 when the factory spec was 9.25.

AJ_72
06-19-2011, 10:19:04 PM
Please don't think I'm trying to be a know it all, far from it, in fact I thought the same thing once upon a time. I've been doing lots of research on a very similar build for a C1500 and I'm not just parroting what I've read on the internet. This is NOT my first engine by a long shot and I've made the same mistakes I'm talking about. Boy, have I! :eek: I've learned from those mistakes and I'm still learning. Having proper quench even on a budget build is one of the more expensive lessons I learned, it makes a difference. It's up to Woody on what he does and I too am trying to give him options based on my experiences and research and the experiences of my friends and associates which spans several decades. I tore into my first SBC 39 years ago this month. I've built some good running street engines and I've built some dismal failures. One of my "successes" was the 383 I mentioned. I built it in 1982, had I known then what I know now it could have been SO much more! We thought it was really something, by today's standards it was wrong from top to bottom but it still worked pretty darn good.


An 8.5 to 1 engine with a short duration cam and no quench is far more likely to detonate than an otherwise identical engine with 9.5 to 1 and proper quench and just because you can't hear it doesn't mean an engine isn't detonating. A TBI engine most certainly CAN detonate when under a heavy load on a hot day. True it's less likely to than a carbed engine but I've had them do it. The ECM has it's limits and when it's pulling back the timing to try to stop the detonation you're giving up power and fuel economy. There's extra power to be had from running a tight quench, especially on the low end where a truck needs it. I understand it's a budget build but the extra bucks for the right pistons will pay off.

It's always cheaper to do it right than do it over.


I understand all that, but Woody already came up with the perfect fix. Run higher octane gas when he plans on towing. ;)

Hippie
06-20-2011, 09:43:59 AM
I understand all that, but Woody already came up with the perfect fix. Run higher octane gas when he plans on towing. ;)

Yes, he could certainly do that but I wouldn't call it the "perfect" plan. Running higher octane when he tows still isn't going to make up for the extra HP, TQ and fuel economy from a more efficient burn he'd be giving up ALL the time but............ His money, his decision. The difference between doing it "cheap" and doing it right is less than $200.

woody80z28
06-20-2011, 11:01:05 AM
Personally I have doubts about how well those would work for proper quench. They're cut away at the center of the quench area. If just a few thousandths on the distance makes such a big difference I'm thinking a big void right in the middle can't help. I think you'd be better off with something like these:

http://www.kb-silvolite.com/images/piston/LKB118.gif

But they're almost twice as much and it's your money not mine. The KB118's pictured are what I just bought for my build. I would have posted the actual pic but it filled my whole 17" monitor when I did the preview.

http://www.kb-silvolite.com/kb_car/performance.php?action=search&mfg=Chevy&EngSize=350&RodLen=5.7

I did some digging and see those KB118's are a 22cc dish. They do have a KB193 that is 12cc but the compression height is better, so the potential is there for much better quench. I need to measure each piston's deck clearance tonight and see where I'm at so I can get the quench figured out EXACTLY with the available head gaskets.

http://www.summitracing.com/parts/UEM-KB193-040/

AJ_72
06-20-2011, 02:56:59 PM
You can't get any quench with them at all which is critical to torque production and detonation resistance.

I think too many people get caught up in the "quench height".

The original intention of the distance between the piston and the head being as small as possible is to eliminate combustion between them, trying to squeeze the flame front out of that area to avoid detonation. Anything less than .050" is sufficient for a high performance engine.

The "squish" that's achieved by running less clearance is not as critical in a cylinder head with the combustion chamber designed similar to the Vortec heads. They promote swirl on the compression stroke.

Besides, without a dished piston that is a "D" shaped dish is contrary to what's trying to be achieved (or obviously a slight raised dome would work, too). Most dished pistons are scalloped out ~.010", and the edge of the piston (which is, maybe 1/4" wide) is the only area the "squish" takes place. Does it help? I'm sure it does. Enough to make a huge difference? Each engine is different, but I highly doubt it. A flat-top or a "D" shaped dished piston are the only two that will help achieve the desired effect.

Keep in mind, these are all attempts to avoid detonation. It's not the be-all-end-all of an engine's detonation problems. There are many other factors involved.

I think too many people try to achieve high numbers on the "bench dyno", not realizing in the real world, it isn't as critical as the magazines and "highly respected" engine gurus make it seem. They're trying to sell books and magazines, so of course everything they write is "critical" and "very important".

But this is all my opinion. Not knocking anyone for trying.

BondoSpecial
06-20-2011, 03:01:13 PM
I used these pistons in my TPI truckster.

http://bondospecial.smugmug.com/1988-Chevy-K1500/assembly/Taurus-caliper-weights-and-350/1028082982_MkzHw-XL.jpg

They were free, the right size overbore, and had only a couple hundred miles on them from a Jasper crate motor.

I have .045-0.050" quench height from the flat parts of the piston top to my quench pad. Is that accomplishing anything?

Hippie
06-20-2011, 05:03:55 PM
I think too many people get caught up in the "quench height".

The original intention of the distance between the piston and the head being as small as possible is to eliminate combustion between them, trying to squeeze the flame front out of that area to avoid detonation. Anything less than .050" is sufficient for a high performance engine.

The "squish" that's achieved by running less clearance is not as critical in a cylinder head with the combustion chamber designed similar to the Vortec heads. They promote swirl on the compression stroke.

Besides, without a dished piston that is a "D" shaped dish is contrary to what's trying to be achieved (or obviously a slight raised dome would work, too). Most dished pistons are scalloped out ~.010", and the edge of the piston (which is, maybe 1/4" wide) is the only area the "squish" takes place. Does it help? I'm sure it does. Enough to make a huge difference? Each engine is different, but I highly doubt it. A flat-top or a "D" shaped dished piston are the only two that will help achieve the desired effect.

Keep in mind, these are all attempts to avoid detonation. It's not the be-all-end-all of an engine's detonation problems. There are many other factors involved.

I think too many people try to achieve high numbers on the "bench dyno", not realizing in the real world, it isn't as critical as the magazines and "highly respected" engine gurus make it seem. They're trying to sell books and magazines, so of course everything they write is "critical" and "very important".

But this is all my opinion. Not knocking anyone for trying.


Wel, how about this then? I agree. ;) :happy:

woody80z28
06-20-2011, 10:50:57 PM
I measured all my pistons and got some odd results. I measured at the top by the lifter valley and by the bottom near the engine mounts:
1: .025 top/.034 bottom
2: .043/.029
3: .025/.036
4: .037/.037
5: .027/.028
6: .039/.027
7: .025/.033
8: .044/.026

This says to me I need the extra .020 compression height of the more expensive KB pistons. But, what does the inconsistency mean?

AJ_72
06-21-2011, 02:13:39 AM
I measured all my pistons and got some odd results. I measured at the top by the lifter valley and by the bottom near the engine mounts:
1: .025 top/.034 bottom
2: .043/.029
3: .025/.036
4: .037/.037
5: .027/.028
6: .039/.027
7: .025/.033
8: .044/.026

This says to me I need the extra .020 compression height of the more expensive KB pistons. But, what does the inconsistency mean?

Piston rock?

The best way to find out what the space is between the deck height and the piston is to rock the piston down as far as it will go for each measurement, then average the two together.

I've only ever measured them near the center of the piston (over the pin as close as I can get) with a dial gauge, rock the piston as much as I can and read the dial gauge at both, then add the two together, then divide by two.

If you look at your numbers per side, then you'll see, 1,3,5 & 7 at the top are all pretty consistent.

1: .025 top
3: .025
5: .027
7: .025

The rest, not so much. LOL

Normal skirt, ring, and cylinder wall will effect the readings, that's why I always rock the piston and find the average.

AJ_72
06-21-2011, 02:22:54 AM
I have .045-0.050" quench height from the flat parts of the piston top to my quench pad. Is that accomplishing anything?

That's a lot better design than the stockers I was referring to.

The air/fuel mixture under the flat part of the cylinder head is being pushed more toward the combustion chamber, which is the overall goal. If you compare that to the shape of the "D" shaped dished pistons though, it's not quite as effective.

http://static.summitracing.com/global/images/prod/large/uem-kb126-020_w.jpg

Not bad in any way, shape, or form. Just not as good. "Free" makes up for that, though.

"Free" is the good four letter "f" word.

If it's working, it's working. ;)

woody80z28
06-21-2011, 09:41:53 AM
These pistons have such a massive dish you can't get very close to the pin location. I didn't think piston rock would have that much effect, isn't the variation a little high?

woody80z28
06-21-2011, 10:33:58 AM
My math brings me to an average of .032" deck clearance, which would make sense if the pistons are a .036 and the block was slightly decked when rebuilt. It looks very good, so that wouldn't surprise me.

That means my compression ration was 8.72:1. The cheap 10cc pistons with the same deck clearance and a .015 head gasket (.047 quench) would be 9.71:1. The KB 12cc pistons with the taller compression height would be .011 in the hole, and an .026 gasket from Summit would be 9.72:1 with .037 quench (and a better quench area).

That points me to the Keith Blacks, but that's over a 2-week wait from Summit or Jegs, and another $60 from Speedway where they are in stock, but won't price match.

BondoSpecial
06-21-2011, 10:39:38 AM
what's the part # on the KB's? Advanceautoparts.com has 15 and 20% discount codes lately that never seem to expire, and they can get a surprising # of performance part #s lately.

woody80z28
06-21-2011, 10:44:21 AM
KB193-040s...dont see them at Advance.

BondoSpecial
06-21-2011, 10:51:15 AM
My other sources in a situation like this would be ebay and amazon. You never know who you'll find w/ them in stock.

Hippie
06-21-2011, 10:54:30 AM
These pistons have such a massive dish you can't get very close to the pin location. I didn't think piston rock would have that much effect, isn't the variation a little high?


I agree with AJ 72 on his measurement method but the H580P's are cheap cast pistons, it would not be out of the queston for there to be a lot of variation.

I don't recall reading this in your earlier posts and hate to ask but have you actually checked your bores for roundness and taper with a dial bore gauge? Are you sure you can get by just doing a hone and replacing the rings and pistons? Sorry, but I have to ask.

My other sources in a situation like this would be ebay and amazon. You never know who you'll find w/ them in stock.

I found my KB118's on eBay at a pretty good discount, they shipped straight from the United Machine (KB/Silv-O-Lite) warehouse.

woody80z28
06-21-2011, 11:07:02 AM
I agree with AJ 72 on his measurement method but the H580P's are cheap cast pistons, it would not be out of the queston for there to be a lot of variation.

I don't recall reading this in your earlier posts and hate to ask but have you actually checked your bores for roundness and taper with a dial bore gauge? Are you sure you can get by just doing a hone and replacing the rings and pistons? Sorry, but I have to ask.

I found my KB118's on eBay at a pretty good discount, they shipped straight from the United Machine (KB/Silv-O-Lite) warehouse.

No, I have not checked them...don't have the tools. The bores look very good though and there should only be about 25k on this rebuild.

Ebay was where I saw Speedway had them. Don't see any other .040s though.

BondoSpecial
06-21-2011, 11:41:28 AM
if you are spending this much time trying to science out the exact CR might want to bring the block to a shop and have them check bore and taper...you don't want to lose any power or consume oil from a ring seal issue...I only speak from experience bc I am often quick to put stuff back together without measuring and I know I shouldn't

woody80z28
06-21-2011, 11:58:46 AM
I know a local guy who will have the tools to do it, I'll give him a call.

Hippie
06-21-2011, 01:32:34 PM
I know a local guy who will have the tools to do it, I'll give him a call.


Better to find out now. I always assume a block will need bored until I can actually check. That way it's a pleasant surprise if it doesn't, not the other way around.;)

I got my KB's through CNCMotorsports on eBay. Good price and they shipped straight from the Mfr., I had them within about 3 days and I ordered them on a weekend.

woody80z28
06-21-2011, 01:58:10 PM
I called KB direct and they are more expensive that way, but he said if I call Summit they can probably drop ship them from KB and still be the same price. He said to act quickly though, cause they only had 600-some in stock. hahaha

woody80z28
06-22-2011, 11:11:43 PM
I had a local engine builder come by tonight and all is good to go with no machine work...just a hone. So as of now the pistons, rings, cam bearings, headers, intake & cam are all on their way. Summit is drop-shipping the KB's so I should have them within a week. I'm going to wait to order gaskets until I can verify the new piston to deck clearance. I've been bugging my bro-in-law to get the long block so I can pirate the heads and all the roller hardware and get this thing together!

Hippie
06-23-2011, 03:24:11 PM
I had a local engine builder come by tonight and all is good to go with no machine work...just a hone.


Cool! :cool: Don't you feel better knowing for certain ?

woody80z28
06-23-2011, 03:49:08 PM
Yeah, and he has the tools to install the new cam bearings too. He also said he could surface the heads off the Vortec block if they need it.

I got tracking numbers for everything from Summit except the pistons.

"Shipping From Manufacturer - Item is waiting to be shipped from the Manufacturer. Shipping times will vary."

retorq
06-25-2011, 12:29:18 AM
I was debating a custom cam for my Tahoe's next engine, I was thinking maybe something between the LT4 and LT4 hot cam specs but ground with an LS firing order ... thoughts??

I was hoping for lots of upper end and mid range power. As it is now I can barely keep it below 2000 RPMs ... I was thinking the LS firing order would give it that "new" sound ...

woody80z28
06-26-2011, 09:45:19 PM
Waiting for my pistons to get here (supposedly Thursday), so I did a little work on the TBI and pressure washed/bed lined the engine bay. The rest of my Summit order did come in though.

Has anyone put 3/4 ton calipers on their otherwise stock-brakes 1/2 ton? Seems popular on FSC, the piston goes from 2-15/16 to 3-5/32".

http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e06aa6a3777e/tn_full_IMG_6322JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e06aa789dc7f/tn_full_IMG_6327JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e07d2f1a0150/tn_full_IMG_6336JPG_Thumbnail1.jpg

retorq
06-27-2011, 09:29:45 PM
Has anyone put 3/4 ton calipers on their otherwise stock-brakes 1/2 ton? Seems popular on FSC, the piston goes from 2-15/16 to 3-5/32".

Tahoe or Pickup?? Tahoe had the bigger piston calipers on the 99 Tahoe Limited, you can just get a set of them from just about any parts store. Might be able to use them ...

woody80z28
06-28-2011, 08:52:47 AM
They are probably the same ones. I know that the 1500 and 2500 calipers are directly interchangeable. It's gonna cost about $100 to do it, and I'm just wondering if it's worth the upgrade.

My "budget" build is quickly approaching double my original plan.

woody80z28
06-30-2011, 07:38:26 AM
NV4500 5spd swap time! Trans shop is dicking me around and is up to $2100 for a built 4L60E when they quoted me 1000-1500 max, and the parts list approval they sent doesnt even have the billet servos or a good converter, etc. So I grabbed this 94 1-ton last night for a steal at $800. I'm taking the 5spd and all required parts, the tcase, calipers, hydroboost and the wiper arms. The 350 runs good, so I'll keep that too. It should be a 4-bolt roller-cam-ready block.

I figure I should be able to sell the rear and maybe front axles, new leaf springs and a few body parts to recoup some cash. All in all with a new clutch and surfaced flywheel it'll probably be under $1000 total. The current clutch seems fine, but I'd probably be better off with a BBC clutch or a Hays "Super Truck".

http://a2.sphotos.ak.fbcdn.net/hphotos-ak-snc6/261865_234914669860780_100000267473982_898840_5249486_n.jpg

455 Formula
06-30-2011, 08:36:45 AM
Get a driveshaft yet????

woody80z28
06-30-2011, 09:33:55 AM
Get a driveshaft yet????
Yup. It was waiting for me yesterday when I got home, but I haven't put it in cause I had to hit to road to pick up the truck. My pistons should be here today too. My to-do list just got longer!

woody80z28
07-05-2011, 09:18:25 AM
Got my Keith Blacks in on Friday. They're almost too pretty to cover up with cylinder heads! My bro-in-law still doesnt have that Vortec block yet, so I haven't started assembly.

http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e127781d9687/tn_full_IMG_6376JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e1277a8ddb24/tn_full_IMG_6378JPG_Thumbnail1.jpg

I am almost done dismantling the parts truck though. Just need to yank the whole drivetrain and get rid of it. Then I'll have a little room again...it's pretty cramped right now.
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e12781ad4071/tn_full_IMG_6436JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e1278152344b/tn_full_IMG_6434JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e1277f16fd5f/tn_full_IMG_6433JPG_Thumbnail1.jpg

AJ_72
07-05-2011, 03:02:22 PM
In case you don't know, make sure you get the right camshaft retainer for the block you own/are building. The Vortec blocks had a different bolt pattern (IIRC, it's smaller) than the older blocks.

woody80z28
07-05-2011, 03:13:25 PM
In case you don't know, make sure you get the right camshaft retainer for the block you own/are building. The Vortec blocks had a different bolt pattern (IIRC, it's smaller) than the older blocks.
That I didn't know. Thanks for the heads up. I read somewhere that all the roller parts were interchangeable, but thats only the lifters & lifter retainer then? What about the lifter dog bones, etc?

BondoSpecial
07-05-2011, 03:22:01 PM
There are 2 cam wear plates that Summit sells under the GM performance line, I just made sure to measure my block and order one w/ the right hole spacing. Other than that I have LTx parts in my gen 1 roller motor so the spiders, lifters, and dog bones should interchange (I used some lifters in one of these builds from a late 90s truck)

Hippie
07-05-2011, 06:08:10 PM
In case you don't know, make sure you get the right camshaft retainer for the block you own/are building. The Vortec blocks had a different bolt pattern (IIRC, it's smaller) than the older blocks.

Interesting, I didn't know that either. I'm using a '96 '880 block but it was a flat tappet TBI motor out of a 1 Ton not a "Vortec". I'll have to check it. Fortunately I have an '87 cam retainer from an L98 and one from a '97 Vortec but if I grabbed one and it didn't fit I would have been greatly confused. Thanks for posting that.

AJ_72
07-06-2011, 08:55:45 PM
Yup. The rest will interchange. It's just that bolt spacing for the plates that's different.

IIRC, they're also thinner metal. They're probably not as strong since they're thinner and they probably moved the holes closer together to increase stability.

woody80z28
07-07-2011, 11:47:14 PM
So.....my bro-in-law brought that Vortec block by today and it's pretty ugly. Looks like the oil hadnt been changed in quite some time. It's only supposed to have 90k on it, but it would have to be 90k of neglect.

Can I clean up the lifters? And if so, how should I go about doing it? I'll try to snap a pic tmo.

Hippie
07-08-2011, 09:39:20 PM
Can I clean up the lifters? And if so, how should I go about doing it? I'll try to snap a pic tmo.


If I have lots of time I soak mine in Berryman's B-9 Chemdip for a few days, drain them and then soak them in ATF or Marvel Mystery Oil as long as possible. Then drain that and soak them in motor oil for a few more days before assembly. If it's going to be a few months ATF alone does an awesome job. If time is short buy new ones then clean the others up and if they're good put 'em on eBay for a few bucks to offset the cost of the new ones. That reminds me, I put a set in the Chemdip last Fall! :eek: It's Hell to get old.:o

retorq
07-09-2011, 10:34:39 PM
Mmm hydroboost ... on my list of sh!t to do. LOL Next up is my AD244 alternator ...

woody80z28
07-10-2011, 11:53:02 AM
Well, I sold the truck carcass to a friend and was showing him the nasty Vortec block and he said he has a set that look good, so I'm gonna trade for them since I'd like to get this engine done quick. I'll keep mine and clean them up for later or to sell...that's a good idea.

ZS10
07-10-2011, 12:17:09 PM
So I've been following this thread as I have a '88 2wd extended cab long box 1500, 350/700r4. Its in great shape but the engine and trans are a little tired. Will be used for towing the car, the odd firewood trip, and camping trips, 2-4000 miles a year.

Even though I realize that even TBI is a step up from carburation, I'm really leaning to the idea of building the engine (possibly 383) with whatever cam I choose and putting a Q jet on it. Just seems so much more simple and cheap...

retorq
07-11-2011, 04:51:21 PM
Won't be too bad since you have a 700, later models had the 4L60 so there was alot more involved. If I was in your shoes I would do the same thing. :D

woody80z28
07-11-2011, 05:26:05 PM
Ditching EFI for a stupid carb? You guys are crazy...

BondoSpecial
07-11-2011, 05:39:45 PM
Haha. My neighbor and I just got our 350 chevy powered camaros on the road and we have taken test drives in each other's cars. He made fun of my EFI until he rode in my car, and until he heard how easily it cold starts and drives away...he has to pedal his for like a minute before it is even driveable. No thanks.

ZS10
07-11-2011, 05:58:31 PM
Ya I understand, if it was a daily driver, I would value the cold starts a lot more, but its only for occasional use. I don't have any place that can tune or modify the tbi programming, I carb I can figure out.

woody80z28
07-11-2011, 11:42:03 PM
This is how the L31 donor came...no intake, oil pan, timing cover or anything. And it's a 2-bolt. Looks like it had coolant in the lifter valley...and cyl#6 was wet. I'm going to have my engine builder buddy take a look at everything and check it out. He's coming over to hone the good block and install my new cam bearings anyway.

On the bright side though, the cam retainer plate is the correct one for my block...haha

http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e1bc0415a9f1/tn_full_IMG_6456JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e1bc0485e985/tn_full_IMG_6457JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e1bc05467816/tn_full_IMG_6459JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e1bc05a99148/tn_full_IMG_6462JPG_Thumbnail1.jpg

I also kept the 350 from the 1-ton truck I pulled the 5spd from. Looks original, so it should be a 4-bolt block and probably roller ready. Haven't cracked it open yet.

http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e1bc014abfb0/tn_full_IMG_6437JPG_Thumbnail1.jpg

woody80z28
07-12-2011, 07:48:49 PM
Heads are both cracked...and he said the lifters are probably past being useable after cleaning anyway.

So now do I pull the Vortecs off the Camaro? haha I know those ones are good.

77nomad
07-13-2011, 03:00:20 AM
So I've been following this thread as I have a '88 2wd extended cab long box 1500, 350/700r4. Its in great shape but the engine and trans are a little tired. Will be used for towing the car, the odd firewood trip, and camping trips, 2-4000 miles a year.

Even though I realize that even TBI is a step up from carburation, I'm really leaning to the idea of building the engine (possibly 383) with whatever cam I choose and putting a Q jet on it. Just seems so much more simple and cheap...
I have a 91 extended cab long box and FWD. Talk about a bitch to park and turn around in tight areas.

woody80z28
07-13-2011, 09:14:13 AM
Checked around craigslist & ebay last night with no luck for real cheap vortecs. Remans can be had for about $500. Summit sells a set of new ones for about $700. AFR's are about $1400 and I could upgrade two engines at the same time...but I'd also need a new intake, valve covers & rockers to convert the Camaro back to a traditional cylinder head, so it pushes the price over $2000.

my24ktrat
07-13-2011, 09:18:55 AM
...Check with Scoggin Dickey Parts Center , they had good prices on new vortec heads , SDPC2000.com ,or 1-800 456-0211 to get a catalog ,hope that helps, :bowtie: DC

BondoSpecial
07-13-2011, 10:40:34 AM
I'd almost consider you selling my EQ vortecs

http://bondospecial.smugmug.com/1980Firebird/EQ-Vortec-Heads/16673638_crMx59#1257116246_hh58jxz

I paid $275 to my door for the pair including the screw in studs.

I have also purchased 1 piece stainless valves ($79), retainers and springs ($60), guide plates ($20) and seals ($30) and can assemble them

The only issue I ran into is they are Gen 1 intake pattern only and they will only seal against a performer RPM or similar large port aftermarket intake (stock intakes will NOT fit)

Here's what a performer rpm looks like against the gasket

http://bondospecial.smugmug.com/1979-Z28/vortec-gen-1-hybrid/17729649_8ms9z8#1353405869_6BnMfXj

Will need some port matching but will work.

I had wanted to use a TPI but its ports are too small to cover these heads and I wound up with a useable set of Gen 1 heads so I am not sure what to do...

woody80z28
07-13-2011, 11:16:39 AM
I'd almost consider you selling my EQ vortecs

http://bondospecial.smugmug.com/1980Firebird/EQ-Vortec-Heads/16673638_crMx59#1257116246_hh58jxz

I paid $275 to my door for the pair including the screw in studs.

I have also purchased 1 piece stainless valves ($79), retainers and springs ($60), guide plates ($20) and seals ($30) and can assemble them

The only issue I ran into is they are Gen 1 intake pattern only and they will only seal against a performer RPM or similar large port aftermarket intake (stock intakes will NOT fit)

Here's what a performer rpm looks like against the gasket

http://bondospecial.smugmug.com/1979-Z28/vortec-gen-1-hybrid/17729649_8ms9z8#1353405869_6BnMfXj

Will need some port matching but will work.

I had wanted to use a TPI but its ports are too small to cover these heads and I wound up with a useable set of Gen 1 heads so I am not sure what to do...

All I have for intakes is a stock TBI that has the wrong center hole angles for an old intake or the Vortec intake I bought from AJ already. So that's probably not my best option. Thanks for the thought though.

I called a few local salvage places and one of them will sell me a pair for $200 and warranty them against cracks. I may need them surfaced, but my engine machinist said that would only be $30 per.

I'd love to use the Camaro's and swap on AFR's but the budget would be getting out of control! haha

BondoSpecial
07-13-2011, 11:18:17 AM
I'm just trying to make my headache yours, that's what friends are for right? lol. I wouldn't really stick you w/ these heads but the quality of their castings and the price was too much for me to pass up, now I have some....alignment issues and I am stuck with a Qjet for the moment.

woody80z28
07-13-2011, 01:04:48 PM
haha Nice try!

boogie
07-13-2011, 09:27:16 PM
Something for you to knaw on:

http://www.competitionproducts.com/RHS-Cast-Iron-Chev-SB-Vortec-Head-170cc_64cc-Assembled/productinfo/RHS12407K1/

Really nice head,complete,for the pair.

You would most likely come out cheaper buying a set of used crack free L31's and have them reconditioned......these RHS's do have thier advantages though.

woody80z28
07-14-2011, 11:50:38 PM
I tore into the 1-ton 350 tonight and see the heads are #810s. A little google searching shows them as 65cc 1.94 350 swirl ports with sodium filled exh valves and rotators on every valve.

Seems like they might be a decent match for my use, but I'm a little worried about 204k on the heads.

Both local guys never got back to me today on the Vortecs...and these 810s are free.

BondoSpecial
07-15-2011, 12:00:03 AM
those have the huge 3/8 stem valves on the exhaust I think...might be ok but sounds like a throw away to use these on a hp minded build. PS 151 posts and not done yet. Get a move on!!

AJ_72
07-15-2011, 12:44:14 AM
I think you're right, Bondo.

I have a set off of a 3/4 HD and it has those same diameter valves. Different casting number (191), but the same concept. The odd thing is, the tip is still 11/32". They literally look like they were ground down by someone turning them in a bench grinder.

1972L
07-15-2011, 05:27:20 AM
Can't you just install thick wall valve guide liners to use a 11/32" stem diameter valve?

something like this?
http://klineind.com/product.php?productid=17839

ps. the last sodium filled valve I bought for a SBC marine head cost somewhere around $50.

woody80z28
07-15-2011, 07:57:03 AM
Well, this thing isn't going to be a screamer anyway...I want low end. I was originally planning to reuse the 193 swirl ports until I found out my engine didnt have them. I read somewhere the HD heads with the valve rotators last forever, so the mileage might not be an issue.

I'll give the local guys one more day to get back to me on Vortecs. If not I'll take a closer look at these 810s.

This project is dragging on forever because I keep running in to road blocks!

AJ_72
07-15-2011, 09:02:36 AM
Hurtles, Woody. Hurdles. ;)

Jump over them keep going forward. You'll get it.

I wish you well in your venture.

woody80z28
07-15-2011, 09:50:41 PM
Hitting the local junkyard tmo to grab a pair of Vortecs for $200. Let's hope they're not cracked!

I pulled the pan off my parts truck engine and it is a 4-bolt...so I'm brainstorming a nasty 11:1 AFR solid roller 383 already. haha That won't be for a while though.

:bowtie:

woody80z28
07-16-2011, 09:51:06 PM
If you have three Chevy 350s torn apart in your garage...you might be a redneck. haha

Grabbed those Vortecs today and they look much better. After the hassle of pulling a junkyard engine out in a field they better be!

http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e223de5781ce/tn_full_IMG_6469JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e223df1010f5/tn_full_IMG_6470JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e223dfcbcb26/tn_full_IMG_6475JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e223e0272772/tn_full_IMG_6477JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e223e080715d/tn_full_IMG_6478JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e223e0f32130/tn_full_IMG_6479JPG_Thumbnail1.jpg

My garage looks like I'm a hoarder.

woody80z28
07-19-2011, 10:10:09 PM
One forward two back...

Got the block honed and it looks brand new. However, both Vortecs I just got are cracked. Magnaflux picked it up. That means four total, and no good ones. WTF

http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e2636a2b4424/tn_full_IMG_6495JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e26369a7a7cf/tn_full_IMG_6493JPG_Thumbnail1.jpg

BondoSpecial
07-19-2011, 10:21:24 PM
I don't think you are going to find usable, used Vortecs. I found an 80k mile 350 TPI engine (good 083 heads) complete with the TPI intake itself, full vehicle harness, and new ECM for all for $350 locally. I don't need another engine but I am sure as hell gonna go buy that on Friday.

woody80z28
07-19-2011, 10:56:14 PM
Given the amount of L31s that left the factory, I didnt think it would be so tough.

BondoSpecial
07-19-2011, 11:21:19 PM
wanna buy my new $99 each 170cc runner vortecs yet? LOL. A performer RPM or RPM qjet covers the ports and fits them, you just can't run a stock TBI base

woody80z28
07-21-2011, 08:59:29 AM
Bit the bullet and just bought a new pair on ebay. The guys feedback looks really good (sells a lot of heads) and they appear to be legit factory GM and still quite a bit cheaper than Summit or GMPD.

This way I don't have to worry about mismatched ports or anything either. My Edelbrock Vortec Performer should match up with the runners perfect.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=330588476951&viewitem=&sspagename=STRK%3AMEWNX%3AIT

AJ_72
07-21-2011, 11:38:48 AM
That's a pretty decent deal.

BondoSpecial
07-21-2011, 11:40:13 AM
Cool beans. Dammit I need to find someone else to pawn off these heads on!!! Arghghghghg

woody80z28
07-21-2011, 01:07:33 PM
Cool beans. Dammit I need to find someone else to pawn off these heads on!!! Arghghghghg

I knew you'd be happy. haha

boogie
07-21-2011, 09:29:37 PM
I am curious if those are genuine GM heads.

BigEd36
07-21-2011, 09:52:01 PM
I am curious if those are genuine GM heads.

From the sellers ebay page:
These Vortec cylinder heads, and all additional parts shown, are not remanufactured and are not "newly rebuilt",
they are made by General Motors Corporation - they are brand new - and not made by an aftermarket company.

woody80z28
07-25-2011, 11:38:39 AM
According to UPS I'll have them tomorrow and I can take a close look. The pics sure look like true GM and this guy sells a lot of them with good feedback. I'm hoping they are legit.

John Wright
07-25-2011, 11:52:45 AM
Woody, will you pull the press-in studs out and put screw-in studs back in? Nice buy on the heads.

woody80z28
07-25-2011, 12:55:16 PM
Woody, will you pull the press-in studs out and put screw-in studs back in? Nice buy on the heads.

Not sure what you mean, John. Vortecs had press-in studs from the factory and these new ones should have the same. I do not plan on changing them...the cam only has .447/.459" lift and won't see a lot of RPM.

The Vortecs on my Camaro still have press-in studs too and have never given me a problem, even with more lift & RPM.

John Wright
07-25-2011, 01:04:10 PM
The Vortecs on my Camaro still have press-in studs too and have never given me a problem, even with more lift & RPM.I was just wondering....I've always just changed them for insurance, I tend to like to twist those small blocks. Doesn't take much effort to pull out the press-ins, cut the bosses down, then tap the holes.

BondoSpecial
07-25-2011, 02:40:56 PM
the cam only has .447/.459" lift and won't see a lot of RPM. Yeah you are not gonna hurt stock studs, I wouldn't think.

woody80z28
07-26-2011, 12:12:36 AM
Local engine guy came over tonight and pressed in my new wrist pins & pistons and installed the new cam bearings. So I plopped a couple pistons in to check deck clearance and ordered everything I needed from Summit to assemble it. Glad I waited to buy head gaskets because my deck clearance ended up being .021-.022 rather than the .011 it was supposed to be, so I went with an .015 head gasket instead of the .026 I had planned on. Quench will be about the same though.

woody80z28
07-26-2011, 11:20:14 PM
Heads are definitely legit GM, I'm happy.

http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e2f79da65152/tn_full_IMG_6504JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e2f79e48f2cb/tn_full_IMG_6506JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e2f79ea1bdcb/tn_full_IMG_6507JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e2f79ef3cb00/tn_full_IMG_6508JPG_Thumbnail1.jpg

Pistons look good at home too!
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e2f79d4aa3b6/tn_full_IMG_6502JPG_Thumbnail1.jpg

woody80z28
07-28-2011, 10:25:19 AM
So, what should I run for a spark plug on this thing?

I see stock 97 Vortec engines use AC 41993 Platinum plugs with .060 gap. ($5.99/ea!)

A stock 94 TBI runs AC CR43TS with .045 gap, but the plug reach is lot long enough for Vortec heads.

I'm using AC R44LTS on the Camaro with Vortecs at .035 gap. ($1.99/ea)

Is the stock TBI ignition good enough to fire a .060 gap with higher compression than stock? Or should I just buy the cheap R44LTS and gap them to the factory TBI spec of .045?

BondoSpecial
07-28-2011, 10:30:00 AM
I have used R44TS on everything and never had a problem but that is not based on science, just on guessing. I would run the stock gap with a stock ignition.

retorq
07-28-2011, 12:37:53 PM
I got the pregapped dual tip ones for a 98 Tahoe when I did my swap. Starts, idles and runs fine for me using my TBI/Vortec setup.

John Wright
07-28-2011, 12:48:27 PM
I would run the stock gap for whatever iginition that you are running. If the stock ign. coil is built for a .035 gap, I expect it to get hot if repeatedly having to build voltage until it fires across a .060 gap. My unscientific opinion, so take that for what it's worth.

woody80z28
07-28-2011, 01:13:50 PM
I did replace the stock coil with an MSD, but everything else is stock-spec.

I'll get the R44LTS and open the gap up to .045 like the stock plugs.

woody80z28
07-29-2011, 07:47:20 AM
I got it all together last night and realized I didn't grab a distributor gear yet for the roller cam. Looking at Napa, it lists the same gear for a 90 Camaro as it does a 94 truck. Shouldn't one be roller cam and the other flat tappet?

https://napaonline.com/Catalog/CatalogItemDetail.aspx?A=ECHDG503_0183266359&An=599001+101990+50012+2012008

Looking up a 97 K1500 it comes up with a different gear, for $60 instead of $10. haha

https://napaonline.com/Catalog/CatalogItemDetail.aspx?A=ECHDG608_0222182949&An=599001+101997+50014+2014029

John Wright
07-29-2011, 08:05:06 AM
90 TPI camaro was roller cam for sure....not sure about the 94 truck with TBI. What did your dizzy come out of? Could it already have the roller cam gear on it.

retorq
07-29-2011, 09:12:36 AM
The 94 Truck will be flat tappet. I've heard that with some factory roller cams you don't have to change the gear ... just a thought.

woody80z28
07-29-2011, 09:28:20 AM
Maybe 90-92 Camaro didn't need the different gear for its roller cam? I'm not sure about the LT1 cam though.

Dizzy is out of my truck, but I'm referencing Napa and it lists the same PN for a 94 Z71 as a 90 Camaro.

I did some searching on thirdgen.org and didn't find an answer either.

All I really need to know is the correct gear to run for an LT1 cam. I'm guessing the Vortec one would work...for $60.

John Wright
07-29-2011, 11:21:51 AM
I know you need a different gear for the billet cams due to the difference of materials, but not so sure about a factory roller....it is still made the same way a flat tappet is, with the exception of the grind.....right?

AJ_72
07-29-2011, 11:46:37 AM
Call either Summit or Jegs, or possibly MSD to get a definite answer.

It's kind of a black hole question because the LT1 didn't even use the dist. gear. I'd assume it's the same as a TPI engine, but you know where assumptions get you.

woody80z28
07-29-2011, 12:02:00 PM
Call either Summit or Jegs, or possibly MSD to get a definite answer.

It's kind of a black hole question because the LT1 didn't even use the dist. gear. I'd assume it's the same as a TPI engine, but you know where assumptions get you.

I did some homework and it's definitely a billet cam from the factory. So here's a question...what did the dist gear on the cam run for a stock LT1 engine, anything?

AJ_72
07-29-2011, 02:04:55 PM
Oh. Duh...

I rescind my previous statement.

There is a shaft that drives the oil pump that runs off the cam gear.

Damon
07-29-2011, 06:05:12 PM
Factory roller cams have distributor gears made of the same material as earlier flat tappet cams. No special distributor gear required. Drop 'er on back in.

boogie
07-29-2011, 06:28:36 PM
GM wants you to use a Melonized steel gear for roller cams that are made of steel. I can only find the part # for the large cap HEI's.

I know they are available for the small cap TBI distributors because I have bought them before.

Give Scoggin Dickey a call, they should be able to hook you up with the correct #

Damon
07-29-2011, 07:54:40 PM
Small cap HEIs already have that gear since they were used during the factory roller cam era. Earlier large cap HEIs use a gear that is so close (possibly identical but using a different name) it doesn't ever cause a problem.

Do and have done it personally many times.

Go install it. Find other things to worry about.

boogie
07-29-2011, 08:33:19 PM
I agree that the stock small cap stock distributor gear should be adequate with that cam,probably melonized anyway

Just me but,if I were using an old large cap HEI,I would purchase the melonized gear for it to run with that cam.

woody80z28
07-31-2011, 11:19:39 AM
Factory roller cams have distributor gears made of the same material as earlier flat tappet cams. No special distributor gear required. Drop 'er on back in.

Ok. I just wanted to be sure that the 87-92 SBC roller and 93-97 LT1 roller used the same dist gear.

1972L
07-31-2011, 05:03:07 PM
GM makes 2 mellonized gears
One for the .490" shaft Large Cap HEI GM# 10456423

and they make one for the small cap HEI with the .430 shaft (TBI/TPI)

The Injected LT1 did not use a shaft driven distrubutor (cam driven opti-spark) but did use a stub shaft with a gear to drive the oil pump.

I don't have the PN for the small shaft mellonized gear but have posted it here before. A quick search will find it.

I used Dow Corning GN metal assembly paste to prevent galling on the gears.

woody80z28
07-31-2011, 10:05:18 PM
Uploaded some pics:

http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e3606be35672/tn_full_IMG_6513JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e3606c42d20b/tn_full_IMG_6516JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e3606c8cf4db/tn_full_IMG_6517JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e3606ce3b6bf/tn_full_IMG_6519JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e3606d35a8e1/tn_full_IMG_6521JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e3606d85ac56/tn_full_IMG_6526JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e3606ddc039b/tn_full_IMG_6527JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e3606e34adea/tn_full_IMG_6528JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e3606eb1095b/tn_full_IMG_6532JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e3606f4cd015/tn_full_IMG_6534JPG_Thumbnail1.jpg

woody80z28
07-31-2011, 10:12:15 PM
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e3606fb99588/tn_full_IMG_6536JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e3607041cb4e/tn_full_IMG_6539JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e36070942a12/tn_full_IMG_6540JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e36070e5d116/tn_full_IMG_6541JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e3607162a65d/tn_full_IMG_6543JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e360722cbd18/tn_full_IMG_6545JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e3607281a236/tn_full_IMG_6547JPG_Thumbnail1.jpg

Had to modify a couple brackets to work with the different Vortec intake pattern. I also heli-coiled and studded the carb holes and studded the carb-to-TBI adapter because if you used bolts that were too long they would hit on the carb pad and bend the adapter plate.

I went to the junkyard yesterday with my bro-in-law to grab some misc stuff and got a single air cleaner stud for TBI too so I can ditch the ugly stock one. It actually came out pretty nice for a bunch of used junk.

retorq
08-01-2011, 11:43:19 AM
Had to modify a couple brackets to work with the different Vortec intake pattern. I also heli-coiled and studded the carb holes and studded the carb-to-TBI adapter because if you used bolts that were too long they would hit on the carb pad and bend the adapter plate.

Looks good. I had a bolt issue with mine too. The stock bolts were too long it went thru the adapter and hit the intake so either the adapter wasn't torqued down or the TBI wasn't torqued down. I got new bolts from the local hardware store that were a tad shorter and worked. :confused:

I mounted my coil on the firewall, it was too cluttered back there with the fuel lines, pressure gauge, etc.

woody80z28
08-01-2011, 04:46:17 PM
Looks good. I had a bolt issue with mine too. The stock bolts were too long it went thru the adapter and hit the intake so either the adapter wasn't torqued down or the TBI wasn't torqued down. I got new bolts from the local hardware store that were a tad shorter and worked. :confused:

I mounted my coil on the firewall, it was too cluttered back there with the fuel lines, pressure gauge, etc.

I was just looking for a pressure gauge adapter today and could only find cfm-tech's one for $40. What did you use? Seems awful simple to be blowing $50 incl shipping on it...when a gauge from Summit is only like $13. haha

And with the pics I saw of the cfm-tech one I'd need to relocate the coil. Should be easy enough though since there are a couple unused tapped holes in the carb intake on the driver side.

Damon
08-01-2011, 06:47:58 PM
Are you using the spacer ring on top of the TBI? THey help if you're using a drop base air clener. If you're using a non-drop base air cleaner (like a 14x3 with zero drop) you don't need it.

Agreed, it does look real good.

Adjustable fuel pressure regulators for TBIs are a bit expensive. Probably don't even need it (keep using the stock one that's built into the TB), but still nice to have for tuning a non-stock combo. Some of the guys over on 454SS.com use a VACUUM ADJUSTABLE one. Knocks down the fuel pressure at part throttle but goes right back up when you nail it. Absolutely requires custom tuning to make it work properly, though.

AJ_72
08-01-2011, 08:02:21 PM
There are modifications on the www.Thirdgen.org site on how to turn the TBI into an adjustable. Should be right up your alley, Woody. ;)

BTW, what did you do to that INTAKE?!?!? :eek:

That thing looks worlds better than it did when I shipped it.

Adjustable Fuel Pressure Regulator for TBI equipped F-bodies (http://www.thirdgen.org/tbi-afpr)

Here's another that may help you in your endeavor.

Adjusting Your Fuel Mixture Via Your 02 Sensor and a Digital Volt Meter (http://www.thirdgen.org/o2tuning)

retorq
08-02-2011, 12:12:12 AM
I used a Summit one that uses std "rubber" line in and out. I replaced the lines leading up to the TBI cause of clearance and all that. I used Jegs pushlock hose it's double jacketed for the feed, and regular fuel line for the return ... I have a pic somewhere, probably on my facebook ...

woody80z28
08-02-2011, 07:41:13 AM
Yeah, I modded the FPR this weekend to make it adjustable. I ground the bottom of the pod so I can get at it with a regular 7/16 wrench without removing anything other than the air cleaner. In those pics I'm using the stock spacer ring, but since I had to make a Summit order anyway I just bought a Hypertech Powercharger...figure it can't hurt.

AJ, I hit the intake with a pressure washer, brake cleaner and then "cast aluminum" VHT. I used the same stuff for my Beretta and it's holding up well. I'm gonna tune it with my wideband that's in the Beretta right now. There's an ADS for $0D available with a wideband hack to display your A/F right in the OBD1 datalog.

I also made my own gauge adapter. Since I had an extra TB from the parts truck I just welded two fittings together and tapped it 1/8 NPT. I put it on the return since there was more meat in the adapter to tap and wouldn't disturb the fuel flow...since it's a return regulator the pressure should be the same in both lines, right? I got thinking after I had it done and I'm not sure it will work. I know a reg after the injectors works fine, but a gauge after the reg might be wrong.

http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e37dea27421c/tn_full_IMG_6550JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e37dea8d0f9b/tn_full_IMG_6551JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e37deadc1658/tn_full_IMG_6552JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e37deb245e28/tn_full_IMG_6553JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e37deb776c92/tn_full_IMG_6556JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e37debc33783/tn_full_IMG_6557JPG_Thumbnail1.jpg

Edit: Yeah...thinking about it again, I'm an idiot. That gauge adapter won't work. The one on my Camaro is right at the return regulator, but it is the pressure side. I don't think the feed fittings would have enough meat to tap the NPT port though anyway, the cfm-tech one must be meatier in the center where the port is and just the back opened up for the fuel line nut. I'll figure something out.

retorq
08-02-2011, 12:09:42 PM
I used these two:

http://www.summitracing.com/parts/SUM-G1711/

http://www.summitracing.com/parts/SUM-800130/

(The pic for the actual gauge is wrong ...)

woody80z28
08-18-2011, 01:16:19 AM
Haven't updated this in a while. Got slammed with OT at work, but it's slowly coming together. Got it back in the truck tonight, so that's progress. haha

http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e4c9748f08f2/tn_full_IMG_6582JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e4c9751d6e76/tn_full_IMG_6587JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e4c975716349/tn_full_IMG_6599JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e4c975b55af3/tn_full_IMG_6604JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e4c976065ac0/tn_full_IMG_6609JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e4c9765ec441/tn_full_IMG_6615JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e4c976c1986a/tn_full_IMG_6620JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e4c9772d54f9/tn_full_IMG_6622JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e4c9779d1272/tn_full_IMG_6627JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e4c9780139a5/tn_full_IMG_6628JPG_Thumbnail1.jpg

retorq
08-18-2011, 01:36:43 PM
Sexy.

BondoSpecial
08-18-2011, 02:02:11 PM
Looks good!!

Kamikaze
08-18-2011, 02:37:05 PM
Been away from this thread for some time. Looking good Woody!

I just have to ask, are you ditching the stock EGR? Or are you going the Vortec route off the passenger side exhaust manifold?

Just curious as I'm about to ressurect my old 89 Sport Truck and have to deal with California Smog checks...

woody80z28
08-19-2011, 07:51:48 AM
Truck is a 94 and doesn't get hooked up to the computer for inspection, so I'm just deleting it. Lots of guys around here swap carbs on their trucks an don't have inspection problems, so I should be fine. I already did a clean EGR delete on the Beretta and I don't think anyone even knew it was missing.

The carb manifold is being a real pain in the ass though. Throttle & cruise cables wouldn't reach so I had to modify the bracket again. Fuel lines won't line up either...I haven't sorted that out yet. TPS & IAC connectors just barely reached. The placement of the TBI is taller and further forward than stock. Looks like I'm going to have to completely re-bend the lines.

Also, I noticed I'm going to need a temp sender since my new Vortec head had a plug in that spot. Are the TBI/Vortec temp senders interchangeable? I'm guessing it's just for the gauge, since my Beretta was the same way with a CTS in the intake for the ECM and one in the cylinder head for the gauge.

Kamikaze
08-19-2011, 12:49:46 PM
Lucky you not having to deal with smog!

John Wright
08-19-2011, 01:12:52 PM
Are the TBI/Vortec temp senders interchangeable? .Could place it in a pan of water on the stove and watch the resistance change with an ohm meter. That may give you an idea of what range the sensor is so you might know if it will work with the gage or not.

woody80z28
08-20-2011, 12:06:22 AM
Lucky you not having to deal with smog!
That's the reason I bought a 94 and not a stock Vortec.
NY are Nazis about 96+.

Could place it in a pan of water on the stove and watch the resistance change with an ohm meter. That may give you an idea of what range the sensor is so you might know if it will work with the gage or not.
That's true, and if the plug isn't the same I could just splice it in.

retorq
08-20-2011, 04:48:19 PM
I used an adapter to put my TBI sensor in the Vortec head ...

woody80z28
08-22-2011, 05:05:58 PM
I used an adapter to put my TBI sensor in the Vortec head ...
Have a PN for it? And the plug in my new heads have a rectangular recess that is smaller than 3/8 and bigger than 1/4. Know the size off hand so I can get a bit for it?

boogie
08-22-2011, 07:56:35 PM
I ran into one of those plugs before. I took a bolt and ground it down to fit so I could remove it.

retorq
08-22-2011, 09:32:40 PM
Have a PN for it? And the plug in my new heads have a rectangular recess that is smaller than 3/8 and bigger than 1/4. Know the size off hand so I can get a bit for it?

I'll look it was a autometer piece though.

LOL I ran into that too ... there was no bit at the local auto parts store. I cut down a 3/8ths short extention ... ground it down actually have a pic somewhere. I think it's on my Facebook.

retorq
08-22-2011, 09:36:10 PM
http://www.nastyz28.com/forum/showpost.php?p=1573087&postcount=34

It was a VDO part ... :D

That's the info you were looking for right??

woody80z28
08-23-2011, 11:22:39 AM
LOL I ran into that too ... there was no bit at the local auto parts store. I cut down a 3/8ths short extention ... ground it down actually have a pic somewhere. I think it's on my Facebook.
Duh, why didn't I think of that. haha

That PN from Napa comes up as a speedo conversion. A google only brought up your thread and a bunch of phone numbers. haha
https://napaonline.com/Catalog/CatalogItemDetail.aspx?A=BK_7011790_0006393668&An=0

retorq
08-23-2011, 12:43:07 PM
Weird ... lemme look around.

woody80z28
08-23-2011, 10:29:17 PM
My old man had a junk 3/8 wobble extension laying around that I filed and removed the plug from the Vortec head. The TBI sensor threads right in with no adapter, so don't worry about the PN.

Thanks! That was easier than expected...haha

woody80z28
09-06-2011, 01:31:12 PM
No updates lately as I've been crazy busy with OT at work...but I lit the fire this weekend! I'm swapping the rear end and need to install both driveshafts before it will move, but it seems to run fine initially.

woody80z28
10-15-2011, 07:17:09 PM
Long time since I've updated...but I've been driving it a while now. Had to put in a higher pressure pump cause it leaned out past half throttle. The o2 is still reading funky, but it doesn't run out of fuel any more. I got an L31 spark table for it and now I'm tuning the VE tables.

The 5spd takes a little getting used to. I can't bang gears like my cars...it won't shift that fast, and the gear splits are huge! 1-2-3 all cut your rpm's in half at each shift...and I hardly ever use 1 since it's so low.

http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e4c9765ec441/tn_full_IMG_6615JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e4c9779d1272/tn_full_IMG_6627JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_drivetrainoverhaul/4e755f4920384/tn_full_IMG_6718JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_newpics/4e9a040e821c9/tn_full_IMG_6858JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_newpics/4e9a03df84c41/tn_full_IMG_6849JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_newpics/4e9a040990a02/tn_full_IMG_6853JPG_Thumbnail1.jpg
http://media.motortopia.com/files/cars/album_newpics/4e9a0417cb085/tn_full_IMG_6861JPG_Thumbnail1.jpg

Damon
10-15-2011, 08:29:36 PM
When you put in a cam with that much overlap I wouldn't trust the O2 sensor below about 2000 RPMs. Tune it for what feels good on the edge of lean in the lower RPMs. Above that point, trust the O2 sensor to guide you.

First gear too steep? Time for bigger tires! You can do that on a truck. On a Camaro it can look a bit silly with 37" boggers on the back end. ;)

woody80z28
10-16-2011, 09:23:23 AM
My 33s are only 1" taller than stock. First gear is awesome when you need to creep it. I even spliced in a rocker switch to the front diff actuator so I can turn it off and have 2WD Low...used it yesterday backing up my driveway in to the garage to unload my new 14-bolt rear. Didnt even need to throttle it at all...let the clutch out and it crawls.

I dont think it's the cam giving the o2 fits. The duration is only 204/207 and the lsa is 117. I've retightened the header bolts 3 times but it still sounds like I have a little leak. I'm gonna grab a copper gasket set from Summit. The ECM is pulling fuel most of the time when it acts lean, so I thought about going open loop to see where I can get. I gotta pull the wideband out of the Beretta too and get it hooked up in the truck.

Damon
10-16-2011, 11:10:32 AM
Sorry, wasn't keeping up with the thread, I guess. I was looking at the engine specs for your Camaro in your sig.

O2 will read fine with that cam, right down to idle.

AJ_72
10-16-2011, 12:19:51 PM
I'm too lazy to read back through the 12 pages to find out, but what trans are you using? Is that the M20 with the 6.xx:1 first gear?

Looks good.

woody80z28
10-16-2011, 04:20:03 PM
Sorry, wasn't keeping up with the thread, I guess. I was looking at the engine specs for your Camaro in your sig.

O2 will read fine with that cam, right down to idle.
The computer-friendliness of that cam is one reason I went with it. Being free from AJ didnt hurt either. haha

The Camaro will be getting OBD1 EFI at some point and I know that cam will need an open loop idle and a lot of work on the VE.



I'm too lazy to read back through the 12 pages to find out, but what trans are you using? Is that the M20 with the 6.xx:1 first gear?

Looks good.
Trans is the New Venture Gear NV4500. 1st gear is 6.34 or 5.61 depending on year. Not sure which mine is.

jasong
10-23-2011, 09:55:22 AM
I would call cfm tech or Lydon at westers about anything to do with a tbi. Have you seen the new tbi truck crate motors from blueprint that come with a chip. Pretty nice.

woody80z28
11-09-2011, 10:06:21 PM
The tick turned out to be a lifter making noise, so I replaced them all with stock LS7 Vette lifters. At $120 I don't think you can go wrong.

Put the wideband on it and the stock o2 was reading rich because it was RICH. haha My injector constant was a little on the low side 75 vs actual 79lb/hr...and this cam I guess wants a little less fuel at idle than the stock one. But it felt lean because it was very lean at tip in. I added a ton of AE and helped the driveability immensely. Still some more tweaking to do, but I finally got the low end torque I was expecting!

Put some black corners on it to make it look mean, too. haha

http://www.motortopia.com/files/cars/album_newpics/4e9f940f9e0fe/IMG_6902JPG_Thumbnail1.jpg
http://www.motortopia.com/files/cars/album_drivetrainoverhaul/4ebb394f085f6/IMG_6945JPG_Thumbnail1.jpg
http://www.motortopia.com/files/cars/album_drivetrainoverhaul/4ebb3960b57f0/IMG_6947JPG_Thumbnail1.jpg

retorq
11-09-2011, 10:14:54 PM
What software is that??

woody80z28
11-09-2011, 10:20:39 PM
TunerPro RT for OBD1.

BondoSpecial
11-09-2011, 11:15:05 PM
Yeay Tunerpro RT! That looks familiar. Glad to hear the lifters were the cause and you fixed it. My TPI truck swap has one lifter that ticks exactly 4 times every time you start it. The truck runs SO well I am hesistant to pull the intake just for that slight annoyance but i have boxes of these oem roller lifters so I really should swap it out.

retorq
11-10-2011, 04:55:53 PM
I have TunerPro RT ... I don't tune my own stuff yet just datalog every so often.

woody80z28
11-23-2011, 09:28:24 AM
Yeay Tunerpro RT! That looks familiar. Glad to hear the lifters were the cause and you fixed it. My TPI truck swap has one lifter that ticks exactly 4 times every time you start it. The truck runs SO well I am hesistant to pull the intake just for that slight annoyance but i have boxes of these oem roller lifters so I really should swap it out.
Yeah...pulling an intake and lashing valves while it's in the truck is a pain.

I'm still playing with the tune, but it's running pretty good! Tried an LT1/T56 F-body spark table (with WOT timing pulled back to 31*) and it is great. It's a bit more timing than most of the truck guys are running, but I've got no spark knock on 87 so far. With a trailer behind it during the hot summer it might be a different story, but I can always splash in some 93 rather than give up the power/efficiency of the added spark. A stock Vortec spark table only runs 20* of timing at WOT! No wonder those things aren't as quick as they should be.

Damon
11-23-2011, 11:14:48 AM
I'd be careful making comparisons between the LT1 spark tables and Vortec tables. The LT1 stuff starts from zero. Anything else that has a distributor at the back of the motor probably assumes 6-8* initial lead at the distributor and then the computer advance is on top of that (even though Vortec distributors aren't really adjustable in the traditional sense). Just a guess.

woody80z28
11-24-2011, 01:05:26 AM
I'd be careful making comparisons between the LT1 spark tables and Vortec tables. The LT1 stuff starts from zero. Anything else that has a distributor at the back of the motor probably assumes 6-8* initial lead at the distributor and then the computer advance is on top of that (even though Vortec distributors aren't really adjustable in the traditional sense). Just a guess.

Actually with TBI and Vortec the initial at the distributor is set to 0. So it's a legit comparison. And idle spark is actually a couple degrees higher on the Vortec table than the LT1 too...but the WOT timing is 10+ more conservative on the Vortec and part throttle is also 6-8 less.

woody80z28
12-11-2011, 06:50:49 PM
Narrowed my erratic super-rich A/F to an inaccurate CTS reading from time to time. I noticed once before the coolant seemed to hold pressure for a long time as it cooled, and today the temp was down to about 100 and it still shot out of the intake when I pulled the CTS for replacement.

So I checked to see if there were any bubbles while running and I did see a couple small ones at idle, but when I gave it a couple quick revs it shot foam out the rad filler. I'm gonna grab a block tester from Napa tmo to see if combustion gases are getting in the cooling system...but the heads and head gaskets are brand new! And the block was fine before the rebuild.

If it is not combustion gasses, what else could be causing the air problem?

retorq
12-11-2011, 07:57:01 PM
Vortec heads?? Old school small block?? Heater core hooked up without that factory heat valve??

That's exactly what mine did when I didn't have my bypass hooked up properly ...

woody80z28
12-12-2011, 07:41:53 AM
Vortec heads?? Old school small block?? Heater core hooked up without that factory heat valve??

That's exactly what mine did when I didn't have my bypass hooked up properly ...

Vortec heads, 94 TBI block and heater core hooked up. Heater core is fed from the intake manifold next to the water neck and and returns to the radiator.

What is this valve you speak of?

retorq
12-12-2011, 09:00:26 AM
http://www.autopartswarehouse.com/images/product_images/thumbs200/4-seasons/74781.jpg

Why return to the radiator?? What's the other port on the water pump hooked up too??

woody80z28
12-12-2011, 10:26:35 AM
http://www.autopartswarehouse.com/images/product_images/thumbs200/4-seasons/74781.jpg

Why return to the radiator?? What's the other port on the water pump hooked up too??

There is a plug in the top of the water pump. Before I touched it, the outlet to the heater came from the rear of the intake and then to the rad after the core. My parts truck was the same way.

Now since the Vortecs do not have a water jacket at the back of the intake I put the outlet up front. But the core still returns to the rad the same way.

I've never seen that valve you posted. Is that Vortec equipment?

retorq
12-12-2011, 07:03:26 PM
It's newer truck equipment, I had one in my 95. My Vortec intake has an outlet in the back, what kind of intake are you running?? Mine pulls from the rear passengers side of the intake and goes directly into the water pump when I'm not running the heater core. If I'm running the core I return it to the pump still. I don't return the heater to the radiator.

woody80z28
12-12-2011, 09:28:57 PM
My intake is an Eddy Performer with no coolant passage in the back. It does have an unused 3/8NPT in the front coolant passage I can plumb to the plug in the water pump as a bypass...apparently this is common practice according to a google search.

88-95 TBIs are different than the 96+ Vortecs in their coolant hose routing, and it sounds like I should run that bypass hose. Hopefully that's my only issue.

I did a coolant CO2 check and got kinda inconclusive results. The fluid turned slightly teal after my test. Not even green, but a slight teal. I checked the fluid at the tail pipe and it turned bright yellow very quickly. I would think if the gasket was 100% good, the fluid should not change color at all...but if it was bad, the fluid should turn yellow. I drew a lot of air through it from the the rad and that slight teal was all i could get.

retorq
12-12-2011, 10:15:38 PM
Good luck, mine was a bitch to figure out. :D

woody80z28
12-12-2011, 10:28:01 PM
Are you talking about a Vortec head swap or a full Vortec L31 engine in a truck?

retorq
12-13-2011, 10:56:39 AM
I did a Vortec head swap on my 95 TBI truck engine, I tried everything that everyone else on the internet said would work and it didn't work for me. I think I even brought it up here on this board and there were a few ideas and scenarios thrown around.

Just so you know I ran that bypass just like you are talking about (the one that it talks about on the instruction sheet that came with the intake even) and still had cooling issues on the passengers side head ... I bet if you get one of those infared temp guns you'll find the same thing I did, the drivers head is OK, passengers head is way hot right in the middle between the two exhaust ports.

woody80z28
12-13-2011, 11:31:36 AM
Do you still have the truck? Any way you could snap a pic or do a diagram as to what hoses went where with your 96+ valve? I'd appreciate it.

retorq
12-13-2011, 01:51:44 PM
Yeah I still have the truck, I took that valve out, that was causing most of my problem, that's what I was saying. :p

I'll look for a pic to post ...

woody80z28
12-13-2011, 02:35:41 PM
Oh, ok. I missed what you were getting at apparently. haha

I looked up that PN and it doesn't show for a 94 K1500, so I shouldn't have one in theory. I know the dash changed in 95 to the newer style, maybe that's the difference.