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18V high compression are slightly higher at 9.0:1 and 170psi at 275rpm.However 18V engines to European emission control requirements ECE 15 are quoted as 170 to 190 or 195psi, although some have said that pressure can't be reached with 9.0:1 compression ratio.The general rule of thumb is that anything more than 10% difference from the lowest to the highest warrants investigation, and in reality they should be closer than that under normal circumstances.2 and 3 down relative to 1 and 4 could indicate a head gasket leak between 2 and 3, where the gasket width is very narrow.
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This may seem a bit pointless if you are going to remove the head anyway, but if the problem is a sticking valve when hot you do need to know which valve it is likely to be first.
Another neat way of diagnosing a sticking valve is with an adjustable timing light.
If that were 100psi also the cylinder would be perfect, which of course won't happen, it will always be lower.
The bigger the difference between the two gauges the faster the air is leaking out of the cylinder.