I'm trying to finalize my parts list many may know I'm building a 370 block with 212218 cam -3.2 forged pistons.. with those pistons and 243 heads untouched I should be around 10.4-10.6 well I have found some 243 but the owner had them milled but milled just enough to get a smooth surface, my question is would that affect the cr that much to where I have to run a different piston to stay at least 10.1 my goals are to have enough compression so out of boost it can still roll but in boost it shines.

 

Depends on how much "just enough to get a smooth surface" is. If all that needs to come off the heads is like .005, then there shouldn't be an issue. You could always make up for it with a thicker head gasket.

 

Engine Compression Ratio (CR) Calculator

What fuel are you going to run? The stock LS3 is 10.7 : 1, no issues with the Gen5 guys going FI.

I am right around 10.6:1 with a Whipple but on E85.

 

heads were milled .005 no more than .006

 

I will be running pump gas with meth

 

You will just have to measure everything when you do your pre assembly to know for sure.