What would be ideal compression on a very cold 1930 V8?? I am getting 25 to 45lbs which is bad but what would be considered very good? Obviously I am getting better when it is warm 55 to 70 lbs still not good.
Martin,
Your compression pressure is a function of your engine's compression ratio, and atmospheric pressure.
For example if the atmospheric pressure in your area is the (standard at sea level) 14.7 psi, and your compression ratio was rated at 10.0:1, you should expect to get a compression pressure of 147 psi.
In 1930 there were three compression ratios available, ranging from 4.98:1 to 5.35:1 with 5.11:1 being the standard.
Using the 5.11:1 ratio you might expect a maximum cranking compression pressure of about 75 psi.
Unless there are other symptoms such as excessive blow by and/or oil consumption, and assuming you live near sea level, the numbers seem appropriate.
Greg Surfas