Thread: 402 heads

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Originally Posted by 70chevybb

I'm still here. I had an old friend give me a 454 and am now going to switch from the 402. I cc'd the 292 heads and sthay are 119cc the best I can tell. The 454 heads are 110 cc which will give me the copression ratio I need. I am still a ways from needing a running engine so It will be a slow build. I am rebuilding the cab of my truck right now. I have the frame fully restored. I will post some pics soon.

Thanks, Wes

sure like to know how you cc a head from GM there is no way it.s 119 ? at best 116cc . i used this head for over 20 years .the ones i built that were 292 casting i had on my mill and cut to a cc chamber i wanted .they never started at 119

I have used the 241,820, and 292 casting heads. All are similar chamber shape ( xtra exhaust shrouding) and all that I have measured are as Pat has stated, 113cc. I have the 292 casting on a 30 over 402. I pocket ported them and added the larger 1.88 exhaust valves. (11/32 back cut/ stainless). They work real well with the current set up. Next week i am pulling them to add different springs as I am switching out the flat tappet cam in favor of Howards pn 12315-10 camshaft. (227/227/.555/.555 110). Its difficult to make compression out of these 402s. I am going to cut .015 off the heads and use the Mr. Gasket .019 head gasket. It should put me about 9.2 to 1 with the KB160 and i'm .020 in the hole. This compression should be fine for this cam. Good luck with your build...