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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?



Van lets try to actually ANSWER your question instead of GUESSING what you have .

heads shaved , by you ? if so what head gasket did you throw it back together with ?



I did not put the motor together. I have all receipts showing parts and head machine work. The receipts shows that the heads were shaved .006". I know I can't count on everything I read (or believe everything Ma Mopar said) but I was just trying to see if I have a compression problem, quench problem, or another problem.



do the receipts show what pistons were used ? i just noticed you said its .030 and stock replacement pistons , which could be anything and will effect the compression ratio greatly .

unless its got KB step heads you can rest asuure that you have NO quench