Snoman.. heres a good one for you.. what cc are these ?

I can find no info on cc's either but I would guess that they are 75 or 76 cc's because all the heads in the 39989xx range are that size. (most are 76 cc's) One source shows them for a 72 to 73 350's and another one shows them as 72 to 75 350's and a third source shows them as 72 to 74 so take your pick.

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They're 76 CC heads.

Al

Forgot, with a stock bore and flat top pistons you should have 9.1 to 1 compression ratio. .060" over would raise it a bit.

Al

I come up with 9.8 to one on a 350 and a flat top piston with no valve reliefs and 9.2 to one for a 327 with 76 cc heads. (all these assume a .030 thick head gasket and bored .060 over) If there is valve reliefs figure on .25 to .5 less depending on size of reliefs. A stock bored 327 would be just a bit under 9 to 1. so the overbore is good for about a .25 increase in compression. ALso if Head gasket is thicker CR would be lower and if gacket is thinner CR would be higher as it also would be if heads have been milled a bit to true them up.

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