[Dragsinger]

Art,

to me, the number is not as important as the consistency between cylinders. With all plugs removed, throttle blocked open, (throttle open so cylinders can receive all the air they want) 5 compression spins is plenty.

You did not say what engine you are testing but 225 is very good for anything. I have never seen a 300 reading?

A couple of notes, as a gauge test you can compare the compression gauge to a air compressor gauge. Example, say your shop air compressor gauge ready 135 pounds, rig a chuck to put that same air pressure to your compression gauge. Both gauges should show the same number.

Also, in an ideal world, engine compression reading would be equal in all cylinders. ( +or - 2% is reasonable for a race engine)