Thread: compression ?
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JFairman JFairman is offline
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Join Date: Jul 2006
Location: S. Florida
Posts: 7,289
The duration and lift of cams installed and where they are timed changes where the intake valve closes at the beginning of the compression stroke so that affects compression at starter motor speeds too.

Mine has 964 cams timed around 1.26mm and compression is around 115-120psi with a cold motor.
If you test the motor hot and like burning fingers while doing it than by the time you get to the last cylinder it will have cooled alot compared to the first cylinder you did and that will throw the comparison off to some degree.

You should also hold the throttle wide open while cranking the starter motor for about 10 seconds on each cylinder.
Old 02-10-2009, 09:57 AM
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