How to check compression

Jim · Post by **Jim** » Tue Aug 31, 2004 5:22 pm

From Jerry:
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Attach a compression tester and open the throttle wide open. Crank engine for 30 to 60 seconds. Take reading at that point.

If you cant compress the fuel air mixture it wont fire. If youre getting under 90 lbs of pressure its time for a ring job.

Post by **noiseguy** » Wed Apr 13, 2005 8:52 pm

If you're much over 115 psi, you need to pop off the head and decarbonize it. If it still reads over 115 psi, then someone has milled the head. This isn't a bad thing necessarily, as it makes it easier to start and run a little stronger. And hotter. Run the next cooler plug.

If you don't own a compression tester, call your local auto parts store and see if they have a "free tool rental" program, ala Murrays, Auto Zone, et al. Or find a buddy who does.