Sounds like I have a rod knock in my daily driver 99 Tahoe, so I will start the tear down Monday. 144,000 miles on the motor, so I will be doing a rebuild. Not having messed with anything newer than a 70 model ( and I've done dozens of those), will I find this motor has the 1 time use head bolts? Is the roller cam likely to be OK for reuse? Anything unusual about these 1 pc seal motors like head gaskets, or timing (can't seem to find a timing mark on the darn thing). Should I expect to find the PM rods? Any heads up on the particulars on these motors would be great. This will give me the opportunity to fix the leaking intake problem common to these. Thanks in advance,
Paul

It should all look pretty familiar. Newer gasket technology, roller cam, crank sensor ring in front of the bottom timing gear, plastic (some say non-reusable) timing chain cover, etc. But it's still just a small block Chevy, really.

Yes, PM rods. If you're just doing rings and bearings, who cares? Slap 'em in and go.

Roller cam gear has a very high likelyhood of being able to reuse everything. It's typically very very reliable stuff.

Head bolts are still reusable. It ain't junk Ford "torque to yield" crap!

There really is no timing adjustment for the Vortec motors. They have a crank position sensor up on the timing chain cover and the pickup in the distributor is just used as a cam position sensor. As such, twisting the distributor won't change your timing like on an older motor. It MUST be in the one and only proper orientation that keeps the cam position sensor in sync with the crank position sensor. If it's off, you'll throw a check engine code. No need for super-special tools. Mark it's position relative to the intake and make sure you drop it back in the exact same position when you reinstall. If it's off, you can move it back and forth a few degrees at a time until the code goes away.

Fresh gaskets on the intake is very common on these motors and will almost always fix the dreaded "coolant leak" issue. Don't over-tighten the intake bolts- literally "screwdriver tight" is all they need. Just enough to compress the built-in o-rings on the intake gaskets. Any further tightening serves only to warp or crack the plastic body of the gakset.

^Damon always beats me to the punch...lol

The vortec 350's are an incredibly durable motor. Its weird though, of the ones I have seen go bad around here its always a rod bearing around 150k miles. I hope I have better luck with my '97 Z71 because I am at the 144k mark as well.

Around this time last year I bought a 250k running vortec 350 out of a 96 1/2 ton. When I took it apart I was SHOCKED to see the bores still had a nice cross hatch in them and no ring groove to speak of after a quarter of a million hard miles (I know the history of the truck). Other than the cam bearings being flat worn out, the motor still had many miles in it.

PM rods: yes, mine were in great shape.
1 time use head bolts: depends on who you ask. I reused mine.
Roller cam reuse: Mine was in great shape. I would have replaced the lifters though had I gone back with stock cam.

Vortecs are famous for a lot of piston slap noise. My girlfriends 96 Burban has raised hell since it had 150k, over 270k now.

PM rods are usually ok. Can not be re-sized due to fractured caps vs cut caps. Crude looking things imo, look like they belong in that old Steve McQueen movie Sand Pebbles where they have the scene of that riverboat engine with the exposed crankcase.

Rear seals are too expensive, I have been known to re-use them and hand make my own seal housing gasket(again too expensive), the pan and VC gaskets as well as the "must be replaced upon removal" front cover. Stick that stuff right back on after a good soft cleaning with a solvent rag. Those GM rubber gaskets are probly good for a million miles.

Intake gaskets are too expensive. I use the Fel Pro. Something like 28 bux.

I use the gm 10105117 head gaskets at 20 bucks each, .028.

Thanks for the extremely helpful info.

I have another Tahoe also a 99 with 188K running no problems except a cold winter start-up piston slap.

I have been told that it may well be the case I can reuse the stock pistons with new rings on freshen honed stock bores because these things wear so little. That remains to be seen once its torn down that far. My mics will tell the story there. How are the heads for wear - guides and seats? Oil pump? Are there any small performance mods I should do - remember its a daily driver. Thanks again,
Paul

Mine just turned 130k and after seeing this thread I'm thinking I should start planning to rebuild mine. Good luck Paul. Let us know how it goes.

PM rods are usually ok. Can not be re-sized due to fractured caps vs cut caps. Crude looking things imo, look like they belong in that old Steve McQueen movie Sand Pebbles where they have the scene of that riverboat engine with the exposed crankcase.

Are you sure?? The rods out of the 98 Vortec I got seem to be normally cut caps. Not fractured ...

Are you sure?? The rods out of the 98 Vortec I got seem to be normally cut caps. Not fractured ...

They can be either way the fractured caps ca be resized by using a bearing with an oversized outside dia. available from both Federal and Clevite , the pm rods are a junk design and all of the ones that I have seem the rod knock comes from the rod relaxing over time and losing the crush on the brg. make sure you have them checked .
The head bolts are torque to yeild and are supposed to be a one time use bolt , if any of you have gotten away reuseing them good for you but you are taking a chance , one that someone who does this for a living won't , you can replace them with old style bolts and use the earlier Chev torque spec [usually do that with the industrial stuff 4.3 and 350 in big lift trucks]

is the crank out of the vortec motors a cast iron crank??

is the crank out of the vortec motors a cast iron crank??

yes

The timing cover is plastic and gets brittle with age, replace it, they are cheap and come with the sealant.

Do not run a double roller timing chain, the knock sensor will pick up the noise and pull spark (think 1996 LT1 chain or the LT4 single roller)

I run ZZ4 balancers on the 96up Vortecs, just be aware that there is a reluctor behind the balancer for the crank sensor, if you run an older style balancer you will have to trim it to allow for the reluctor clearance, otherwise the belt will not align perfectly with the pulleys.

Yes, you can resize the rods, ARP wave locks are cheap too.

The stock vortec head gasket is .026".

The stock vortec pistons are dished, The H345np makes a good replacement
http://www.jegs.com/i/Sealed%20Power/844/H345NP/10002/-1?CT=999 or for a few bucks more you can they offer the same thing but coated
http://www.hawaiiracing.com/?page=shop/flypage&product_id=3525

Vortec rings are metric (expensive), using the H345 you can use standard (inexpensive) rings. The factory rings have a low tension oil ring, everyone has thier favorite rings, use what works for you.

The Vortec oil pump has a 3/4" pickup, not the normal 5/8".

You are not going to be happy when you see how much crud accumulates on the lower intake manifold. this is "normal".

For cam upgrades this is hard to beat if you use you truck, like a truck.
http://paceperformance.com/index.asp?PageAction=VIEWPROD&ProdID=22922

Above all, no matter what you do to it, get a tune. Give the tuner the engine specs and intended use.Ship em the ECM, and they can change shift points, fuel cut off points, tranny shift points, line pressures etc.....One phrase they might or should ask you is: do you want to remove the "torque management".
The correct answer to this is "Yes". TM is GM's tranny saver program that pulls timing etc... to save the weak stock 4L60E. TM sucks from a performance point of view.

Also do your self a favor, and replace the weak poppet valve spider. GM has a new one out that eliminates the problems of the older version(s).

Thanks again, but you lost me at the end there. Get a tune? Ship someone my ECM? My imagination tells me this is something to do with recalibrating the computer and I don't know jack in that department. I figured the computer knows how to adjust itself but I be wrong man. Help help help.

Also if the stockpistons are dished and the 345NPs are flattops, I assume it will bump the compression and screw with the knock sensor too?

Thanks again, but you lost me at the end there. Get a tune? Ship someone my ECM? My imagination tells me this is something to do with recalibrating the computer and I don't know jack in that department. I figured the computer knows how to adjust itself but I be wrong man. Help help help.

Join up at http://www.tahoeyukonforum.com/forum/ ... lots of good info there on full sized Chevys with Vortec motors.

It takes more than a screwdriver and a 9/16" wrench to tune one of these things,
The stock GM fuel and spark curves are very conservative to say the least.
The computers will/can make minor changes for some modifications, like a new exhaust or a cold air intake.
But to unleash the true potential of these things, it's got to be done electronically.
Here's an old thread from FSC showing how Torque management works, the pics won't work since the forum upgrade, but they are simly graphs of the timing curve. if you read the captions next to the red x's you can get an idea of whats going on.
http://www.fullsizechevy.com/showthread.php?123667-Torque-Management-Pics-of-how-it-works

Join a truck forum that deals in EFI tuning, read and learn, it really not that hard, it's just a bit overwhelming at first, like learning a new language.

Thousands of guys have been down this road before, keep your build conservative so you won't have problems with a tune down the road. (for example, Don't stroke it, raise the compression to 12.5 to 1, with a Wild cam, and expect it to run worth a damn.)

All the vortecs I've torn down had cut rod caps. The LT1's and some LS engines have fractured caps.
Make sure to use the FelPro intake gaskets with compression stops. And keep DexCool out of it, run the green stuff. I'd spring for a new timing cover, it's a pain to pull the balancer, etc. when you install the old one and it leaks.
I rebuilt the 350 in my '97 with flat top 4VR pistons and an LT4 cam. Compression is right at 10:1. I've never heard any pinging, but the computer may take enough timing out to stop it. It's sure not down on power!

boy this is getting into a lot of money on tuning software and parts for a stock rebuild....how many stock rebuilds need wave locks? they made it a pile of miles the first time round with what they had...

Wave locs are $54 from Jegs
http://www.jegs.com/i/ARP/070/134-6403/10002/-1?CT=999
The Pro-series are the $$$ ones

Cheap insurance for a smallblock spinning 5500 RPM in a 5400lb truck

Wave locs are $54 from Jegs
http://www.jegs.com/i/ARP/070/134-6403/10002/-1?CT=999
The Pro-series are the $$$ ones

Cheap insurance for a smallblock spinning 5500 RPM in a 5400lb truck

Wave locks aren't really the plan for PM rods they tend to add stress to the bolt bosses and housing bore [on some rods you can even see the ripple they cause in the boss ] PM rods have problems with stress and that's what causes the loose brg in them in the first place the relaxing of the housing bore over time as the stress relieves

Tore it down today. Yep, cut caps so they can be resized. All internals look great, but #2 rod is spun for sure. What are the specs on that LT4 cam - sounds interesting. I read up on that tune info - some amazing stuff there!
Paul

I'm with Louich, performance rod bolts are probably a bit over the top on a stock type rebuild. There are a lot of BBC's out there with factory rod bolts spinning well above 6K and they're the same diameter as these in this 350. Chunk the rod with the spun bearing, these PM rods are plentiful and you should be able to find a single somewhere. Definitely have 'em all resized, but I'd probably leave the factory rod bolts in place.
There's no timing mark on these, but there are a few tricks to getting the dist stabbed correctly. You'll find quite a few knowledgeable folks on your trucks at http://www.fullsizechevy.com/forum.php. Some will tell you that you'll need to visit a dealership to get timing zero'd in, but I never have. If you get it close, the computer will do the rest.

My truck rarely spins over 4000 RPM. When I tow, I sit right at 3000 - 3300 RPM at 70MPH.

You need a Tech2 (GM diagnostic tool) to see what the timing is. As mentioned, you need to get it close, so the engine will run without the SES light.

I redid my distributor and accidently did everything correct the 1st time so it ran fine. Then I figured out I'd time it cause it was running cool and seemed to be a little weak. I backdoored a Tech2 and checked the CPS setting and I was at 3. Spec is 0 to 2, +/-. So we set it to 0. Made no change in how the truck ran. I wouldn't pay $$ to have someplace put the tech2 on my truck. "Someplace" is typically a dealer. The Tech2 costs a fortune. My low rent diagnostic tools don't show the CPS parameter.

My truck rarely spins over 4000 RPM. When I tow, I sit right at 3000 - 3300 RPM at 70MPH.

You need a Tech2 (GM diagnostic tool) to see what the timing is. As mentioned, you need to get it close, so the engine will run without the SES light.

I redid my distributor and accidently did everything correct the 1st time so it ran fine. Then I figured out I'd time it cause it was running cool and seemed to be a little weak. I backdoored a Tech2 and checked the CPS setting and I was at 3. Spec is 0 to 2, +/-. So we set it to 0. Made no change in how the truck ran. I wouldn't pay $$ to have someplace put the tech2 on my truck. "Someplace" is typically a dealer. The Tech2 costs a fortune. My low rent diagnostic tools don't show the CPS parameter.

the snap on scanners will read them too.

Final word is the crank is junk, worn down as much as a rod bearing thickness. Took out the oil pump and every other bearing (cam too) in the motor with all the metal shavings. Already have all the new parts for reassembly except for the oil pump. So much confusion out there - I see a standard volume Melling M155 but how do I avoid the weak housing pump - don't know good from bad?

Also, why am I seeing some who recommend not reusing the head bolts? I cleaned and checked every one and they look perfectly fine and identical to my old school bolts except for a smaller head. The ones under the valve cover area are plain but the short ones along the bottom edge are a silvery plating. They have 1/2" socket head but otherwise they are identical to early 70's.
Paul