I have a 350, .30 over with TRW Forged pistons, if I gave you these numbers would you be able to tell me?
Either with a 64cc or 72cc head.

On the top of the piston it shows in a bigger font L2256
littler font 99295 .30

 

If the decks are uncut on your block your CR should be real close to 8.6:1 with a 76cc chamber head and 9.7:1 with a 64cc.

Lonnie

 

That would be 8.9:1 with a 72cc.

 

According to my reference, TRW L-2256 pistons are flat top, forged, with four valve reliefs (totalling about 5cc), so with a nominal compressed head gasket thickness of 0.039" and a deck height of -0.015" under 76cc heads, you static would be 8.76:1. The same parameters with 64cc heads would increase the static compression to 9.90:1.

If you want to run the numbers youself, download this worksheet:
Engine Calculator.xls

 

Well the block was decked last year and I am getting New Heads, does this change anything? Thanks for the replys.:hail:

 

Obviously, the deck height alteration will change the static compression. It's all in the calculator...

 

Honeslty I have no clue about this stuff. Thats why Im askin.

 

That's quite alright. There are a lot of things about which I have no clue. If you download the spreadsheet, the calculations are built in so all you have to do is enter your specific engine dimensions and get the results.