Redoing my original 289. I'm .040 over with flat top pistons. I had the heads shaved to 50 cc. What am I looking at for compression ratio? How do you figure out my comp ratio. I'm thinking 10.1. Am I close?
As pointed out you still need to know piston cc, deck clearance (how far is the piston in the hole) and which head gasket you are using to know compressed gasket thickness. Then you can use the calculator above to determine Compression.
Using the somewhat standard rules of thumb for some of the numbers in case your engine is already put together and you didn't measure some things, I get 9.92:1. It could be a bit more if you have no eyebrow flat tops or less if you have 4 eyebrow flat tops.