I picked up my 383 short block today :cool: I'll get around to some pics eventually. This is a STREET car shooting for 385 or so HP. This car will occasionally see 6500 RPM's when nobody is looking... Can I please get some feedback on my top end (nothing purchased yet):


Dart Iron Eagle Platinum Heads (64 cc / 215 intake runner - 10.3:1 or so CR)
Victor Jr Intake
Holley 750 CFM
Roller rockers (1.6 ratio)
1 7/8 headers into 3" collector into 2.5 exhaust


These things will NOT change:

cam LSA 112*, 218* intake / 226 exhaust at 0.050" (278*/284 advertised)461/.468" lift --- the cam looks wimpy, but it has a steep ramp that helps...
3.73:1 gears behind my TKO 600



EDIT: The LSA is 108*, NOT 112*. There is 4* of timing ground into the cam to give me a lobe center of 112*.

Thanks!

I'd be looking at the 200's rather than the 215's, but that's just my opinion. If you plan to have the heads ported then the 180's would be an even better choice for your cam selection.

OK, let me ask this same question a little differently. My cam has an advertised power range of 2000 to 5700 RPM with 6200+ redline (Crower Beast cam specs - Hot Street Beast pg 24 of their catalog). The victor Jr that my machinist recommends has a power range of 3500 to 8000 rpm. The RPM intake works in the 1500 to 6500 RPM range.

My machinist suggested a 750 min CFM carb. I did a quick internet calculator & and it ranged from 725 to 775 CFM. I see his point. I figure that my current Q-jet is a 750 cfm (?) which should be fine. It is a new reman unit by a reputable shop & it works flawlessly.

Maybe I'm doing this with too much emphasis on the paper specs, but I'm thinking that the 200 cc Darts, with the RPM intake & Q-Jet should be more than adequate for my setup. Any thoughts on this?

Edited to restate the question more coherently ;)

That cam's too small, imho.

Get onna the generic 280/230, 109/107, .480" lift cams instead! Or their equiv. of it!! It's the 230 duration at .050" thing here is all....

(Hydraulic Intensity = 278-218=60! Vs 280-230=50!!).............

Q-Jet RPM type intake..

Heads a tad big to me?? I'd go with 195's or so...

Same deal with the headers, only b/c you aren't really going to rpm her ALL that high it seems....

As always, jmho..

pdq67

OK, let me ask this same question a little differently. My cam has an advertised power range of 2000 to 5700 RPM with 6200+ redline (Crower Beast cam specs - Hot Street Beast pg 24 of their catalog). The victor Jr that my machinist recommends has a power range of 3500 to 8000 rpm. The RPM intake works in the 1500 to 6500 RPM range.

My machinist suggested a 750 min CFM carb. I did a quick internet calculator & and it ranged from 725 to 775 CFM. I see his point. I figure that my current Q-jet is a 750 cfm (?) which should be fine. It is a new reman unit by a reputable shop & it works flawlessly.

Maybe I'm doing this with too much emphasis on the paper specs, but I'm thinking that the 200 cc Darts, with the RPM intake & Q-Jet should be more than adequate for my setup. Any thoughts on this?

Edited to restate the question more coherently ;)

Agreed on the RPM intake and 200 cc heads. The Qjet can be made to work but I gave up on them 15 years ago due to the lack of parts availability and PITA to work on when dealing with the primary side, so I like Holley carbs. You may even entertain a street avenger 770, the vac secondary would be a good choice with the mild cam.

My vote for your current cam choice is positive, I don't believe you need a big honkin cam to make good power.

Rust,

Imho, a 280/230 is NOT a big honking cam in a 383...

3.73 rearend gears and a TKO-600 to boot..........

I don't like the 278/218 here is all unless Crower is measuring them differently??

I can see a 268/218 cam like CC's good old 268HE ALL day long... But NOT a 278/218 jobber...
As always, jmho..

pdq67

PS., you want a little-bitty cam then I would stick this solid one in it!!

Clevite; PN 229-1998 -- 258/219/270/229, 114/110, .456"/.479" and it need's .022"/.022" lash. And use 1.6 ratio rockers on her!!

D2k say's uncorked, 401hp at 5,000 rpm and 481t at 3500 rpm so go from there..

Talk about a work horse motor, imho.....

:p I stand by my original post. It sounds like it isn't the ol 214/224 that you're thinking of, and for a STREET (again, his words) cam it may be a pony or two down at 6000 and above, but from 2500 to 5500 it should have an excellent pull. With the correct heads it should make his 385 HP.
In case you don't care for the old 214/224 cam we build a 351W, mild ported smogger heads, performer intake, that generic cam, pump gas in a 2800# car with a 5 speed, it ran high 12's much to my suprize. Check out my thread about engine combinations in the HP topic here to see what can be done with the puny 204/214 cam. ;)
Naturally, just my opinion, I respect yours. :)

Thanks guys. I was told that this particular cam is a bit deceiving on paper. My machinist uses this cam quite often and he continues to get good feedback on it in the 383's that he is building. He wouldn't budge on his suggestion when I pushed for something bigger, so I'm trusting him on this one. I'm still going with the 1.6 ratio rockers ;)

He just scared the heck out of me when he told me that I would be too lean on the top end with an RPM intake & my Q-Jet. I would agree if I was running an old worn-out Q-Jet with jetting from the emission era - but mine is none of those... It is fresh & has decent jets/rods. I have room to go larger on the jets/rods if I am lean.

I'm thinking that as long as I don't hang out in higher RPM's for too long, I should be fine with the 200 cc Darts (10.3:1 CR), RPM intake, Q-Jet, and 1 5/8 headers. Simple and effective...

Am I missing anything?

He may be thinking high RPM with a small amout of throttle blade opening, such as 4500 RPM and running only on the primaries. A pyrometer or oxygen sensor setup will help determine if his concerns are reality or not. Come to think of it, an oxygen sensor setup like from Innovate can help you dial that carb to perfection and would be a good thing to have.

Not to be-labor the point, but a 278/218 cam is still a 278/218 cam no matter how you look at it, imho!!

Now just maybe it's like this, I don't know??

Theoretical here is all!!

278/218/160 vs a 278/218/140???

Advertised, duration at .050" lift and finally duration at .200" lift.............

pdq67

I picked up my 383 short block today :cool: I'll get around to some pics eventually. This is a STREET car shooting for 385 or so HP. This car will occasionally see 6500 RPM's when nobody is looking... Can I please get some feedback on my top end (nothing purchased yet):


Dart Iron Eagle Platinum Heads (64 cc / 215 intake runner - 10.3:1 or so CR)
Victor Jr Intake
Holley 750 CFM
Roller rockers (1.6 ratio)
1 7/8 headers into 3" collector into 2.5 exhaust


These things will NOT change:

cam LSA 112*, 218* intake / 226 exhaust at 0.050" (278*/284 advertised)461/.468" lift --- the cam looks wimpy, but it has a steep ramp that helps...
3.73:1 gears behind my TKO 600


Thanks!

215cc heads way too big for that tiny 218* cam
1 7/8" headers Way too big for that tiny 218* cam.
1 3/4" would work better, and 1 5/8" would too
200cc heads with high velocity like AFR or Canfield(Jegs alumuinum) would be a great jead choice. Or some of the 170-190cc heads ,
Big heads and big headers need a bigger cam and more compression.
6500 rpm with a 218* cam,, engine might spin that fast, but power will quit about 5500 rpm. The big heads and headers won't help,, and the soggy bottom from the big ports will kill the performance of your combo.

the 112 lobe separation angle with the short duration would dictate a small header for me. 1 5/8" maximum primaries for the street. as well as a dual plane intake such as the rpm. i've seen the base 383 combos work well with 200cc iron eagles with your compression range and cams in the 235-240@.050 range,, but idle quality starts going away there. and they like 2800+ converters minimum with those bigger cams.

if the cam and carb aren't going to change,, then maybe some smaller heads like vortecs should be fine on a 383 base engine. but if you want growing room for later,, the 200cc iron eagles. jmo.

the 112 lobe separation angle with the short duration would dictate a small header for me. 1 5/8" maximum primaries for the street. as well as a dual plane intake such as the rpm. i've seen the base 383 combos work well with 200cc iron eagles with your compression range and cams in the 235-240@.050 range,, but idle quality starts going away there. and they like 2800+ converters minimum with those bigger cams.

if the cam and carb aren't going to change,, then maybe some smaller heads like vortecs should be fine on a 383 base engine. but if you want growing room for later,, the 200cc iron eagles. jmo.

Agreed. I trust the cam, but I also don't - so the 200 cc's are my choice in case I decide the cam really isn't big enough.

Here is the final combo for consideration:
Same cam with 1.6 roller rockers
Dart 64cc heads with 200 cc intake runners
@10.3:1 CR
Edelbrock RPM intake
Q-Jet
1 5/8 long-tube headers

Hiperperformance ran the Viritual Engine Dyno for me (thanks again!) & predicted:
461 ft*lbs @ 3750 & 434 hp @ 5500
a 2" carb spacer bumped me to 467/451 at the same RPM's...

The torque curve looked nice and didn't drop below 400 until the engine spun up to 5750 to 6000 RPM's. For as much as I believe the software, it confirms that my Q-Jet is big enough & that I am better off keeping this motor under 6000 RPM's.

Now I'm wondering if the 3.73's are too steep - especially behind the TKO 600.

Im with the other guys,either theres not enough cam or too much head for a "street" 383.

Seems like as soon as the heads are starting to flow w/ the cam,the cam is going to run out of steam.

I had a 357 in my 87 IROC with hopped up Vortec heads,Perf. RPM, and a 218/224 @ .050 and .495/.502 / 110 Comp roller cam in it and it would run awesome untill 5500. Your cam is similiar in duration and less lift so I see it dieing about 5500 as well.

Just my 2 cents.

That cam in a 383 is gonna sound like a stocker I think.

Ok, I'm a dumb @ss.

Somebody was kind of enough to explain to me the difference between LSA and lobe centerline. My LSA is 108* with 4* of advance ground into it to give me a lobe center of 112*. I think I said that right...

Does that change anybody's opinion for better or worse?

the lobe separation angle is what's ground into the cam. it is the distance measured arround the cam,, in CAM degrees from the exact centerline at max lift of the intake lobe ,, in relation to the exact centerline at max lift of the exaust lobe. once ground it can't be changed without a regrind. and then it's iffy at best. another cam choice is a better route.

basically,, narrow (lower) lsa numbers when compared to wide angle numbers (higher),, will shorten the rpm spread from peak torque to peak horspower. that's the easiest way to say it without going into alot of tech.

lobe centerline is just that,, the very center of the max lift point of the cam lobe.

but it is also used for describing where it is physically measured/degreed to,, when installed in the engine,, in relation to the crank position,, at the degree point after top dead center at max lift centerline of the intake lobe or after bdc at max lift of the exaust lobe,, in relation to crank position. it's measured in CRANK degrees here. so it can be confusing.

most quote the intake centerline as a degree/install point,, for trying to figure out and idea of cylinder pressures or engine operation ranges or conditions that will be seen,, when using the term this way. or saying weather it's advanced or retarded from the cam card or lsa specs,, etc.......

as an example,, a cam with 110 lobe separation angle,, installed @ 4 degrees advanced will put the intake lobe centerline @ 106* after tdc and the exaust lobe centerline @ 114* after bdc.

in other words,, a cam on 110 lobe separation angle installed at 110 degree's max lift intake lobe centerline after tdc is said to be installed "straight up" in relation to the crank position. hope it helps.

LSA is ground into the cam, changing the advance only changes when the timing events occur in relation to the crank, e.g. advancing the cam opens the intake valve earlier.

Close LSAs like 108* pump up the midrange, but at the cost of some top end and bottom end. I like a 218* cam with 110* LSA for a nice street 350. Your cam will feel great around the street and be a lot of fun to drive, but the top end will drop off, negating some of the benefit of the higher flowing heads. But not all the benefit of the heads. Internally stock LS1s can make 400hp on the engine dyno with a pathetically tiny cam (duration ~ 200* @ .050). A lot of that is due to the excellent heads.

So if it is truly a "STREET" car, you cam will be fine with a good set of heads. But not 215s. Oh yeah, shift around 5,700-6000, not 6,500... you'll only go slower with a later shift.

stock LS1s can make 400hp on the engine dyno with a pathetically tiny cam (duration ~ 200* @ .050). A lot of that is due to the excellent heads.
LS-1's ports flow very well and at a high velocity.
So picking the right head is essential.
And Iron Eagles aren't the ones.