327 SBC compression ratio question

I have just picked up a 327 short block, flat top pistons with the valve relief, 2 bolt main truck block. I have a choice of heads both sets have 1.94 intake and 1.50 exhaust valves. One set has 66 cc combustion chambers the other set is 74 cc. My question is with stock flat top pistons what would be the compression ratio difference between these heads?

 

theres a little info missing but with out doing any math and shooting off the top of my head id say 8.5 ish and a little over 9 for the 66's

 

The original heads yielded 10.25 to 1 don't remember the CC 58 maybe!

 

Originals with 64-ccs had 10.25. Rebuilder pistons hang down in the hole about .040. Put a .040 head gasket on with the 66-cc heads and you'll need a mix of good fuel and hot ass spark to make it run without pinging. If you try the 74-cc heads you'll not get shit for power. The camshaft will come into play here also. If you choose a cylinder head just call comp cams and they can reccomend a cam for the needs of your combo. The effective cylinder pressure that the cam generates will help in this situation. It would be good if you could use a head with 69 to 70 CCs. Really you need to plan the engine carefully>>>>.

 

Don't trust the factory c.r. ratings--most of the 327s that claimed 10.5:1 were really around 9.7:1.

 

Depending on piston deck clearance..,
Zero deck (best case senario)= 9.3865:1
.020 deck (average senario) = 8.9749:1