Just did this with my friends compression tester. Car was run for awhile but not up to operating temperature.We got 170 in all four cylinders? Did he read the gauge wrong? Seems a bit high seeing as how it was mentioned that 150 was normal. We did let the engine crank more than four revolutions maybe until it stopped going up?....it was four revolutions for the test was it not? Also we did not have the choke out...was it supposed to be out. I think I remember that when doing compression tests on American cars the carb throttle valve was supposed to be wide open?