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HybridZ

choosing a set of heads


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i came across a set of mid 70s corvette heads. with 0 miles on them for 150.00. first wanted to see what i would do for me. block is a 355,hyperutectic pistons, cast rods and crank. cam is 220@ .040 planing on goin with a 650cfm carb and air gap intake.

what to know will these heads hurt me more than help

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Mid 70's might be emmissions heads, which would be a bad thing. No way to know for sure though unless you can give us some casting numbers to look up. There should also be a casting mark at the front of the head, most of the decent heads will have two rounded humps cast here, looks kind of like the McDonalds golden arches. Other heads will have triangle, or rectangular shaped casting marks here, but again, no way to tell for sure without having some casting numbers to go off of. ( Casting numbers will be located in the valve train area) Hope this helps,

 

Mike

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Smaller chamber will be beter for more power, compression, squish and should be less likely to detonate at a set compression ratio. I had a look in Vizards chevy bookd earlyer and this head number wasnt one of the ones he sugested to use. There is a lot of good info on the web, and on your side of the world good after market used iron heads can be picked up for very little. I wouldnt bother with early factory heads in your situation.

 

Douglas

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After market heads kick butt. Those old stocker just don't do it anymore. The head will work ok but you will lose 30 or 40 hp!

 

And by the time you install springs, bigger valves, screw in rockers, port work, and a valve job you will have an old set of heads that cost more than a better performing new head.

 

If you want to build a mild 350 then use flat top pistons, 76 cc combustion chambers, 180 to 195cc intake ports, and a 210 to 220 degree cam. 76cc combustion chamber will make 9 to 9.25:1 with a 350 flat top engine.

 

If you want to build a hot 350 then use flat top pistons, 64 cc combustion chambers, 195 to 215cc intake ports, and a 230 to 240 degree cam. 64cc combustion chamber will make 10 to 10.25:1 with a 350 flat top engine.

 

Consider the following heads from summit racing or jegs: dart iron eagle, world products sportsman II, trickflows, AFR, or GM vortec heads.

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Guest Phil1934

I shoud have mentioned the heads he got from pbm even had a Canfield logo on them. Sort of like those Gen'l Kinetics cam everyone reboxes. You might as well get them from PAW.

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