Re: compression test
The ovious question is "why not just work it out the conventional way?".
To work it out using actual compression is very difficult. You need to know your leak down rate and volumetric efficiency at idle, plus your inlet valve closing angle, stroke and rod length to convert from dynamic CR to static CR, to name a few, but......
having said that if you run the engine at idle and measure the cylinder pressure and the manifold vacuum:
e.g compression pressure = say 42 PSIA, manifold pressure = 18"Hg;
18"hg = 8.8 psi, so absolute pressure going in (14.69- 8.8) = 5.89 PSIA
DCR = 42/5.89 = 7.26
with a little trig on the inlet valve closing angle of say 70°, stroke 3", rod length 5.09".
Dynamic stroke length =2.2"
CR = 9.5
Like I said it's easier and more accurate to work it out the conventional way:- using a reasonable calculator that takes into account toplands, dishes/domes, gaskets, deck to deck heights, etc.
Go the Brisbane Lions