Final Engine Compression Ratio?

billsdartgt said

the .029 is above deck

the dome volume is what I was missing for the online calculators found on the net, using this one https://butlerperformance.com/n-12872-compression-calculator.html with a 10cc volume for the dome the noted SCR moves from 10.31 to 11.07, changing from a 68cc to a 72 cc for the head and using felpro's range of .049 to .059 for compressed gasket thickness.

Values I used:

bore dia. 4.030 (based on piston size)
stroke - 3.58 (stock)
cylinder head volume - 68 up to 72 (I read somewhere these were what had been seen in the past)
Dome volume -10cc
Deck clearance - .029 (I assume the measurement I took at the flat is this number)
Compressed gasket - .049 to .059
number of cylinders - 8

Click to expand...

Yes, use the measurement at the flat for the deck clearance. BTW, using your calculator, I get 11.6 for a 6 cc net dome volume, .029" above deck, .050" head gasket, and 72 cc head chamber. Both the deck clearance and dome volume should be entered as negative numbers in your calculator. And realize your domes have been milled a bit so the 10 cc net dome volume is too much IMHO. And head is probably more like the 68 cc number so now you're pushing over 12:1.

If it really was 10.3, then maaaaybe the 702 cam. But I am pretty sure you are up well past 11:1. Ready for a bigger cam while maintaining good low RPM torque!

Hope it works out well.