Question: Cylinder Heads???

[Vette79]

I need some feedback on Cylinder Heads. I am putting together a Project which involves replacing the Cylinder Heads, Cam, Lifters, Pushrods, Roller and Timing Chain, Water Pump, Pulley's, Upgraded Jets on the Quadrajet Carburetor, Thermostat, Intake Manifold, etc. I already have headers with dual exhaust. I have all of the pieces and parts already except for the cylinder heads and pushrods. These are the cylinder heads that I am looking at purchasing: http://www.airflowresearch.com/180sbc_sh.php Would these cylinder heads be a good fit or are they too much for my project and why? Here are the specifics to my COMPCam Kit: http://store.summitracing.com/partdetail.asp?part=CCA-K12-238-2&view=1&N=700+

 

[Glensgages]

..... just-guessing here, but I doubt that with such a fairly-mild cam (.462"/.469" lift, 218*/224* @ .050" lift ) you'd need 2.020"/1.600" valves, although the port-volume is probably good:
they'll be better'n the boat-anchors that came on the car from St. Louis!

 

[Vette79]

I know that too big will hurt performance and if I am only using 70% of what the cylinder head is capable of then I am also wasting money. These are the smallest cylinder heads offered on AFR's website for a SBC 350.

 

[Glen Braxton]

Maybe think about getting your hands on a Desk top dyno program, search google, it's floating around out there. The DD, can be argued to be flawed, but it can show some direction with various combos.

The AFR's seem to be about $1400 and change plus shipping. The Edelbrocks are about $1040 I think, and have reduced flow compared to the AFR. It might be an acceptable match for your cam, plus keep $400 in your pocket for something else.

Lots of options to keep you awake at night, wondering which path to take......

 

[wishuwerehere82]

Those head might be overkill for the cam you are going to use. Some good 1.94 heads would probably be a better fit for the RPM range. Though Chevy did use 2.02 heads on the 302 Z28 engines.

I built a 302 from a 69 Z28 a long time ago. Which is a 327 block with a 283 crank.
It had stock 2.02 chevy heads from the factory, which was their choice for the engine.
By the time I was finished, I had 12.5:1 pistons bored out .060" over stock, 3/4 race cam, dual point ignition, headers, Holley carb and Street Dominator intake. It ran about 500 HP, but carboned the plugs if run at street speeds in 3-4 days because of the high compression. It ran good up to 8000 RPM, but was really poor on 96 octane gas milage with 4.10 gears.
So for your cam's RPM range of 6,500 RPM, you probably don't need to go with 2.02 inlets, but it won't hurt anything. If you were to stroke it to 383 Cu-In., they would pay off better and you could easily get into the 500 HP range with the AFR 195 CC heads.
http://www.carcraft.com/techarticles/ccrp_0611_performance_engine_combinations/index.html

 

[Tom Bryant]

I am looking at the AFR 180s for a .030 over 302 engine I'm planning for my '59. My cam is a lot bigger and I'm looking at 10.3:1 CR as ideal. If you are going to use these heads (which I feel are a great piece) I'd step up the cam a notch or 2 and consider a lower (higher numerically) rear gear. Call AFR for recommendations with your combo. I'm running a very similar cam to yours on my 9.3:1 355 with ported 76cc iron 1.94 heads in my '69 stepside. I haven't lit a fire in it yet but it's getting close. I feel that if I had more cam I'd need bigger heads or if I had bigger heads I'd need more cam. My suggestion for your combo would be to use the GM iron Vorec heads. They are the best flowing iron small block head that Chevy ever made and they will make the old 2.02 heads look like boat anchors even though they only have 1.94 intakes. They would be a great match for your combo with fantastic performance all across the rpm band. They are also one the the best performance bargains out there. GMPP has them drilled for either Vortec manifolds or old style.

If you must go aluminum I'd use the smallest intake runner cross section available to keep port velocity up so you don't have sluggish responce in the off idle and low rpm range with your cam selection. Keep in mind that you need to run 1 point higher CR with an aluminum head to get the same power that you would make with the exact same head cast in iron. This is due to the superior heat transfer of aluminum. 10.3:1 cr is do-able with aluminum and 93 octane pump gas. If you want to run regular or middle grade at the most stay with the iron Vortecs. They have the fast burn design combustion chamber and are much more tollerant of low octane fuel and higher CR than old style chambers.

Tom

 

[Curtis]

I looked at the site you suggested for the AFR heads and it confused me.. There are two different listings for intake port flow for the afr heads.. both are completely different. Accordingly being an AFR site, they did not show you heads that flow better than theirs.. The GM vortec flows the following on 164 cc ports : .100 -59 .200 -118 .300 -177 .400-217 .500-226. All these numbers top the afr and the edelbrocks they are compared to. REad this article http://www.superchevy.com/technical...etebuilds_testing/0312sc_dm15_copy/index.html and it talks about having heads that are too large. The point is that with too big of runners, you lose velocity of the charge going to the cylinders which results in less than the optimum fuel mix and lower power, expecially at mid rpms where street vehicles are operated... The vortecs for example with the smaller runners than afr, outperform the afr because of the high velocity of the ports, and they even have smaller valves. Dangermouse tested many heads including the AFR, and they incidentally did not out perform the cheaper vortecs. I have read about some tests where going to the 2.02 valves decreases flow because of valve shrouding the path of the mixture into the cylinder because it is so much closer to the side of the cylinder. So there you have it. MY twenty cents worth. Do the research, you will be glad you did. good luck . And if you do go to vortec, use the vortec specific intakes available. with the raised intake ports of the vortec, the old style manifolds do not match well at all to the vortec heads.

 

[Vette79]

Keep in mind that I already have some hardware. Performer intake manifold with a 1980 Heavy Duty Quadrajet with larger jets (75). I am looking for cylinder heads that will compliment this project with hardware that I already have and the Cam Kit. Any suggestions?

 

[Curtis]

The perfect compliment and biggest bang for the buck to that XE262 cam is the vortec heads. you can get a complete kit to fit your engine (including manifold, bolts, gaskets etc.) for less than the AFR heads alone. I did it and have had no problems. Look here for prices. http://www.sdparts.com/categories/e...heads/SDPCVortecCylinderHeadsandHeadKits.aspx
If you want torque that will fry your tires and jam you in the seat, this is it.

 

[Vette79]

How about a recommendation other then Vortec. I also have 1.5 roller rockers that will be used.

 

[Vette79]

Would these be a better choice? http://www.jegs.com/webapp/wcs/stores/servlet/product_10001_10002_69940_-1

 

[toolman0114]

What about Dart Iron eagles, that's what I run on my 74 -355. 65cc.

 

[glen242]

I am happy with my TF 195cc heads on my 383. Check their flow numbers, 0.500 lift flow is almost identical to AFR. Cam only goes to 0.500 lift (cc X274 hydraulic).

 

[Vette79]

Yep, I think the AFR heads will be fine. AFR 180cc heads are designed to be efficient with small camshafts.
• Efficient Cyclinder Heads + Small Camshaft = Gigantic Torque, Monster Horsepower and Great Street Ability.
• Compare our Low RPM Torque to the Competition.
• Don't be fooled by the other packages that require Camshafts 15° to 20° larger at .050 to get near our peak Horsepower

Here are the number compared to Vortec.

The GM vortec flows the following on 164 cc ports :
.100 -59 .200 -118 .300 -177 .400-217 .500-226.
AFR heads flow:
.100 -not listed .200 -138.300 -198.400-240.500-260.

 

[Vette79]

So will a Edelbrock Performer RPM Intake Manifold with a Stock Quadrajet Carb fit without hood clearance isssues while using the original stock dual snorkel setup??? And would there be any need to upgrade from a Performer to Performer RPM?

 

[fine69]

So will a Edelbrock Performer RPM Intake Manifold with a Stock Quadrajet Carb fit without hood clearance isssues while using the original stock dual snorkel setup??? And would there be any need to upgrade from a Performer to Performer RPM?

I can attest that it did not fit without some mods on mine. It looks like the '79 has a bit more clearance.

 

[Hib Halverson]

For heads, you picked the best choice, IMO. Air Flow Research makes some fine aftermarket aluminum heads. Tony Mamo, the top engineer there, is not only a Corvette guy (he owns a C5 Z06) but his knowlege of air flow and what makes an intake port really work well is unmatched. If I were building a motor, be it a Gen 1, 2 , 3 or 4 Small-Block, AFR is the head I'd use.

As for the camshaft, the only reason I'd use a flat tappet hydraulic is if I absolutely could not afford a hydraulic roller. There is no comparison as far as performance increase and low-end power.

 

[Vette79]

Thank you guys for your responses. All I have left to get are the heads now. Can't wait till it gets warmer...