Trying to figure out the compression in my '70 GTX with original 440 (without tearing the motor apart). I'm getting tired of fighting pre-detonation and want to try and do something. First thing I want to do is figure out my CR.

I have ported 906's that are shaved .006" (assuming 78 cc's), .030" over bores, stock replacement forged pistons. If I can find what the average depth of the pistons are (and look at compression thickness of my head gaskets) I can closely estimate my CR.

What's the average depth in the hole for a '70 440?