Compression ratio

[vje55]

I have a 340 plus 040 (4.080), Head is 66.5cc, pistons are TRW L2316 040 (I think they are 6cc) they have the 2 valve reliefs and a hole in the centre ??, piston sticks out 0.055", head gasket (felpro) 0.050??, stroke is standard (3.31') can some one tell me the comp ratio please!

BJ

 

[RustyRatRod]

According to the numbers you gave and the calculator at the United Engine web site you have 10.919:1.