I recently took my car to a dyno and pulled a disappointing 231.66. The engine guy there said that it had much more potential and the cam, carb, and intake were all wrong. The engine specs are:

1987 Chevy 350 bored .040 over
Dart Pro 1 aluminum heads (Part # DRT-11320010P)
Crane Cams (Part# CRN-104224) - Duration at .050 214/220, Lift .452/.465
Crane Cams hydraulic roller lifters
Dart Intake Valve Springs (Part# DRT-22000010)
Dart Exhaust Valve Springs (Part# drt-21311600-8)
Comp Cams rocker arms (Part # CCA-1412-16) 1.52 Ratio
Comp Cams pushrods (part# 7808-16)
Speed Pro pistons (Part # TRW-L2256F40)
Holley Brawler 670 cfm carb
Edelbrock Performer Intake, made for quadrajet but running an adapter/spacer for squarebore.

What would a better intake, carb, cam combo for this engine?

 

I'm not at all surprised that this engine is a disappointment.

You're putting these terrific heads on there, and then sliding in a copied copy of a generic copy of a copied generic copy of a copied generic cam-shaped object that isn't in any way matched to the heads in any form or fashion; it's just the cheeeeeeeeeepest thing you can buy that says "cam" on the box, and still nobody will quite go to jail for fraud on account of printing that there.

Furthermore, that generic cam-like thing is a flat-tappet, and is not compatible with roller lifters. If something hasn't already destroyed itself, it won't be long. You should NOT run the motor any more AT ALL with that severe mechanical mismatch in it.

The head number you gave is for a bare 200cc casting w/ 64cc chambers. You need valves, springs, and all the supporting hardware; rocker studs, retainers, seals, keepers, shims, etc. I'm guessing you already have studs and valves since it's running but you don't say what they are, other than, the rockers are for 3/8" ones. I'm not a big fan of the valves Dart supplies with those heads.

Unfortunately that combination of those "rebuilder" truck pistons and those heads will give you rather low compression; ideally you'd want pistons without the extra .020" of "rebuilder" clearance that those have, and to have had your block decked closer to zero and squared up. A stock 350 TPI motor with aluminum heads had 58cc chambers; you're WAY below stock compression. Kinda too late for that now though. Gotta work with what you've got in that department at this point.

The intake spring number you gave is for a stock replacement, light-duty spring. Not adequate for much of anything. Those springs need to go, period.

The exhaust spring number you gave is for an exhaust VALVE, not a spring.

I'd suggest:

• Manley 10765-8 exh valves https://www.summitracing.com/parts/m...66-8/overview/ (about the same price as the Dart, but they have undercut stems: SIGNIFCANT flow increase)
• Manley 10766-8 int valves https://www.summitracing.com/parts/m...65-8/overview/ (see above)
• LS6 valve springs https://www.texas-speed.com/p-1383-l...od-to-550.aspx Set them up at 1.750" installed height.
• Comp 787 retainers https://www.summitracing.com/parts/cca-787-16/overview/
• Comp 503 valve guide seals https://www.summitracing.com/parts/cca-503-16/overview/
• Comp 648 keepers https://www.summitracing.com/parts/cca-648-16/overview/
• Comp 4709 spring seats https://www.summitracing.com/parts/c...9-16/overview/
• Comp 4757 shim set https://www.summitracing.com/parts/cca-4757/overview/
• Comp 1617 self-aligning roller rockers https://www.summitracing.com/parts/c...7-16/overview/
• Comp XR270 roller cam https://www.summitracing.com/parts/c...22-8/overview/ (there are also others, in this same general range, that would work well with the rest of your combo; but this is about where you're going to want to be, with the low compression)
• Intake manifold https://www.summitracing.com/parts/edl-3701/overview/
• Distributor https://www.summitracing.com/parts/d...20bk/overview/

Use your existing carb. Should be just fine; at least it's not "The Problem" the way the cam and valvetrain is.

What you have to work with is, a low-compression motor, with BIG flow. You don't need to cam it to the moon to get power out of it. In fact it will probably go slower, have a soggy bottom end (EEEeeeeeeeeewwww) and no "leave", if you go to wild in that area. Err on the conservative side.

You didn't tell us anything about your gears, converter, exhaust system, etc. Sometimes those things make as much OR MORE difference to how fast THE CAR is, than a dyno # for the motor. We don't race dynos after all.

I love spending somebody else's money sometimes.

 

I could be missing something but those pistons spec out at 1.56" compression height. Isn't that standard 350 SBC stuff with a 5.7" rod?

 

That roller cam is still bigger than the 196/206 roller cam that I made 272 rwhp and 330 rwtq from a 9.6:1 Vortec head 350 with. That was through a 4L85E and GM 9.5" 14-bolt while turning a clutch fan as well.

I am more interested in what you are running for headers and exhaust. If you are running say stock manifolds and a LG4/L03 Y-pipe I am suprised it would even make 200 rwhp.

I would consider a performer rpm intake. It is worth a solid 10-15 hp over the performer intake.

Furthermore your pistons are performance oriented pistons unlike the reduced height ones Sofa is talking about.

670 cfm is not a bad carb and is adequate in soze for 400+ HP.

That cam is mild but with those heads should not have an issue making about 350 hp with a smooth idle and a strong torque curve from idle.

What is your distributor setup? I would start with about 12° initial advance and shoot for 34° total by 2,800 rpm as a starting point.

How was the air/fuel ratio? If it is too lean or too rich that can drastically harm output as well.

An unlocked higher stall torque converter and dynoing in a gear lower than 1:1 can also hurt dyno numbers.

Head gasket choice can kill compression but I bet that engine is still 9.6:1 or better. If you are not zero decked, I would use a set of GMPP Vortec 350 gaskets. The are small bore, 0.028" compressed composites that work very well with aluminum heads. I have them on my 11:1 383.

I would try a set of 1.7 rocker arms on the intake and 1.6s on the exhaust. Those roller tip comps are junk. Get a full roller with a roller trunion.