What PSI is "good compression"

[chugbug]

I would think being run hot or more like overheated could hurt the rings enough to hurt compression .

 

[chugbug]

Went out to the shop and compared my compression gauge to my air compressor like Brad suggested, the gauge came up 20 psi under the compressor . That would put my new 346 at 140 psi and if I can seal the thread leak maybe I will have found the problem . But first I'll compare it to a couple other gauges and see what I get .