340 compression test

Hi cudatom.

Young family takes priority at the moment so slow going.
I plan to put the 340 into my daily driver in place of a 318 so am focusing on the exhaust that needs replacing anyway.
2.5" with X and block huggers.

Anyway, without pulling heads off mine and from what I can see down the spark plug holes I think I have pistons like in this pic.
http://www.forabodiesonly.com/mopar/showthread.php?t=33448

So I have been doing some reading and guessing/calculating in the hope that I can run the 340 on the high octane unleaded here in the UK.

Have been reading about Dynamic Compression Ratio and the dramatic affect that the cam I have will have on lowering this from that of the Static Compression Ratio (with pistons like these - circa 12.5:1)
I think (hope) that the high psi readings on my compression test will be as a result of the lifters having bled down and causing the intake valve closing event much earlier than the cam actually is closing when the engine is running and oil is fed to the lifters to keep them up when under load.
http://www.empirenet.com/pkelley2/DynamicCR.html

There is one calculator on the internet that I can not find just now that I was fiddling around with that when I had it setup with known values such as bore and stroke and a few guesses like the cc of the dome pistons so it was reading 12.5:1 as a SCR then switched to the values that the cam provides to calculate the stroke length after the intake valve closes I was getting a DCR of around 8:1.

I'll look for the calculator and post when I find it.

I guess your 10.72:1 is going to be your SCR.

Good luck and let me know how you get on please.