Looking for Info / Specs on Obsolete Mopar Piston

nm9stheham said
It makes sense if I understand it. If the reference surface (the quench flat) is x" down, then you computed the 'perfect' cylinder volume as if the piston was a flat top. Then you measured the actual open volume with the dome in place, and the difference was the dome volume of 19.5 cc.

One more measurement is needed, which can be done in one of 2 ways:
Method A is to measure from the center of the pin to your reference surface.
Method B is to measure the distance of the reference relative to the deck when the piston is at TDC.

Method B is preferred, as it will compensate for the block having been decked, or for any rod length changes made. Method B should be easy if the lower end is still assembled.

With this last piece of info, it will be easy to run an SCR computation for you.

Thanks for your response.
I went over my data and discovered a math error.
Here is the data I'm using:

Head gasket:Felpro 1008: dia=4.174 inches, measured thickness=0.044 inches, Vol=0.61 cu in=9.87cc
"Perfect" cylinder is 0.425 inch below block deck. (block deck to quench flat)
Vol=5.53 cu in=90.62cc
Burette measured 80.4cc to fill chamber
Dome volume = 90.62 - 80.4 = 10.22cc
Quench flat on piston is 0.010 inches above deck.
Cylinder bore = 4.070 inches
Cam data: intake closes 62 degrees ABDC.

I plugged these numbers into the Diamond Racing Compression Calculator and it gives me a CR = 11.15.
The Wallace Dynamic Compression Calculator gives me a DC = 9.00:1
Dynamic cranking pressure = 186 psi.
I did a compression test before pulling the motor. Readings were 185 to 200 psi.
I'd like to get the CR / DC down at least one full point to be pump gas friendly (91 to 93).
A local engine builder said they may be able to machine the pistons down.
Given this combination of parts, how would you proceed?
This motor has 3500 miles on this build. Still has the crosshatch pattern in the bores.