Here are some numbers for a static compression & leakdown test on my 340 T/A engine. Cylinders are bored .030 over, I don't remember the head milling, but I'm supposed to have a compression ration of 10.2:1. The cam is a Comp Cams Hi Energy 268 (218° @.050 / .464"). The engine has 40,000 miles on it's rebuild.

Compression-static
1) 141psi 2) 140psi
3) 145psi 4) 140psi
5) 140psi 6) 142psi
7) 140psi 8) 141psi

Leak Down Test
1) 6% 2) 5%
3) 5% 4) 3%
5) 2% 6) 4%
7) 5% 8) 5%

Thanks!

Compression numbers are all real close this is good and leakdown is less than 10% also good. I'd say compression is not 10:1 for only 140 PSI. My 9:1 451 pumps up much more than this.

cylinder pressure seems a little low but leakdown is good for the miles. if it drives and runs good i wouldn't touch it.

All good in the 'hood ex as said comp #'s are low. Alot of SCR #'s have not been actually measured/calculated & are lower than people think

Everything looks fine, the only thing wrong is the compression ratio. Probably less than 9:1

It looks good! I guess nobody noticed your in Colorado Springs.
Air pressure is only about 12.2 psi?
Doing the dynamic compression calc backward with an intake closing point of 60 abdc, I get 10.25:1 static compression ratio?

If you were at sea-level (14.7psi), cylinder pressures would be about 169 psi.

6000 ft sure does make a difference!

Thanks guys! And yup, we're just a tad over 6,000' here.
'Preeshadit!