Sounds low and I'm sure some others can quote figures from a service manual. But I pretty sure you shouldn't see anymore than 10 psi difference from low to high reading. Most engines depending on the compression ratio that I have had were up around 150 psi.
Make sure you are propping the throttle open when taking the readings, and take ALL your spark plugs out...plus, make sure the engine is warmed up when you do the test. Aaron
