The cylinder that you are checking must have the piston travel up and down 4 times are more.
8:1.
A compression test.
4.000x3.750 with 8.5:1 compression
A compression test will determine which cylinder(s) are at fault.
There are a lot of variables when checking compression...basically the idea is to have all cylinders within 15 lbs of each other. Double check your readings.
the same way all modern combustion engines work with fuel ,compression, and ignition
Yes, they should fit ok. 305 heads should bump up the compression a little.
If the oil and water galleys match up, and it bolts to the block fine you should be good. You will probably get a very high compression ratio from this set up.. I had a small block .305 and I switched out the stock 64cc heads for a pair of 49cc heads I got a much higher compression and gain in hp. You really need to analyze the heads and block in question and surf the forums for a better answer.
Anywhere from 80, up to 180, depending on ther compression ration, effective compression ratio, and how many miles on the motor. Lower than about 80, is getting low. Also, you are looking for a cylinder that is really low, compared to the rest. 30 lbs., or more, lower. This would indicate a dead cylinder.
It varies from 145 to 370, depending on a lot of variables including compression ratio, cam profile, and head design.
305 Small Block Chevy engines typically were 8.6 compression ratio and would use 87 octane fuel.
Your small block Chevy 377 is only getting 16 pounds of pressure because it might having a problem with pressure.