Thread: head frustration

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I'm trying to decide on a set of heads for my 1974 Chevy 350 w/ 4 bolt mains. I'm having trouble getting straight answers from manufacturers and suppliers. Maybe somebody here can answer some of my questions.

They offer some of these aftermarket heads with the valves at different angles. What's the advantage? I am running flat-top speed-pro pistons with Fel-pro gaskets.... what do you think I need? 14*, 23*, 18*, etc?

why do nearly all of them say that they need the edelbrock Victor Jr. intake or similar? I plan on running an offenhauser single plane, what's the difference?

Why does it seem that none of them are able to run stock length valves? Why do they all need +.001 valves?

any shed light on the topic is appreciated.

I would run the 23 degree heads. The 18 and 14 degree are for serious performance high rpm motors. The longer valves are most likely for proper spring height and to get valve train geometry correct. Overall the longer valves won't hurt you, but many of the higher performanc heads often require offset intake rocker arms.
If you can use a victor jr. intake with the heads your offenhauser single plane will also work with the heads it's similar. The heads your looking at are for a high rpm motor, you will loose alot of lower rpm torque.

They shouldn't be meant for too high of RPMs. They are 72cc chamber, w/ 200cc runners, 2.02 and 1.6 valves.... listed for typical street rods.

If this is a street motor, I'd drop down to 190 cc intakes.

Johnny listen too them....

The different valve angles are for more exotic applications. The general design was 23 degree while racing/nascar uses more 18-14 degrees stuff. This help promote air flow less restricted in the rpm range intended for use.

Also any change from 23 degrees will require special pistons (different releifs)

I agree with Tech on the 190cc heads for street. If you go too big on the cc's it's just the same as using too big of cam....

If you are using this vehical on the street I would strongly suggest the Edelbrock RPM AIR GAP manifold. One you gain slow speed torque and you need that.....Two it makes in most cases as much hp or more than it's single plain counterpart againts the old design! you'll be much happier

Thanks for the info... good stuff. I thought 200cc runners were a bit much also.

Found a set of 64cc chamber, 192cc runners, for 1.6 and 2.02 valves. Aluminum heads..... these would probably be better, eh?

also for added info-I'm going to be running crane 1.5 roller tip rockers, Manley steetflo valves and I plan on running a lunati Voodoo cam 262/268 duration, .468/.489 Lift (in/ext) w/ Lunati hydraulic lifters and springs..

Thanks again.

johnny, let's back up for just a minute here. I'm seeing a mismatch of parts in your selections.

Assuming a 0.030"-over 350 (355), flat-top pistons with 4 cc's of valve reliefs, zero deck, 0.039 gasket, those 64 cc heads are gonna result in a compression ratio of 10.5:1, way too tight for the cam you picked. You'll almost certainly never get the motor to run on pump gas without pinging.

Use the free information that's out there from dyno tests to put your combination together and you'll be far happier with your combo. Take advantage of the money other guys have spent. Look for healthy torque numbers and disregard horsepower for a street motor.

Among many others are the tests done by Air Flow Research. I was just looking at their site and saw a test on a 355 Chevy using their heads with 180 cc runners and 74 cc chambers, with a low-buck Comp Magnum 270 hydraulic cam. It makes over 400 ft./lbs. of torque from about 2,700 r's to over 5,500 r's with 469 ft./lbs at 4,000 r's running on 93 octane pump gas and a c.r. of 9.5:1. Just as a matter of reference, this motor made 430 hp.

With flat-tops w/4 cc reliefs, zero deck, 0.039" gasket and these 74 cc heads, you'd be at 9.45:1, so that's probably the combination they used to do the test, rounding off the 9.45 to 9.5.

Go here, click dyno tests at the top of the page, then click small block chevy. http://www.airflowresearch.com/

Also, go here and pick out all the 350 combinations.
http://www.ryanscarpage.50megs.com/combos1.html

Take a look at the flow numbers on those 18 and 14 degree heads you were looking at, not just the cc's of the intake runners. You should see some significantly higher numbers on the 18 and 14 degree heads. Those heads also require some hard to find intakes in some cases you might have to fab your own.
Sounds like your heading more in the right direction now though.

Thanks again. I appreciate the help. I have never used aftermarket heads when rebuilding an engine. I usually just use the originals. I'm still feeling it out. Want to have a serious ground pounder when I'm done. The motor is going in a 29' Model A hot rod.

Looking at the World S/R Torquers either 67cc or 76cc. Anybody with experiance in these?



Features
170cc intake runners. 30hp over most OEM castings
2.02/1.60 Valves or 1.94/1.50
67CC OR 76CC combustion chambers
Dual pattern raised valve cover rails
Accepts all early and late model accessories
Hardened Seats
Screw-in studs
Z28 valve springs
TRUE bolt on installation!!
Pre 87 applications