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Post by rocketj25 on Feb 28, 2012 16:12:02 GMT -5
I'm planning on doing my first cylinder leak down test and was wondering if anyone could give me some info. What is a good percent, time to freshen percent, etc. Also what air pressure works the best when checking the leak down of one of these engines? Thank you for your time, Rick
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Post by hammerdownpower on Feb 29, 2012 16:54:04 GMT -5
A brand new engine should be in the 2-4% area. Once you are over 8-10% you have power escaping. Plug the tester in according to the instructions and loosen both rocker arms. You can take the pushrods out so they don't fall into the motor. The air will push the piston down to the bottom of the bore. Here you can check your leakdown with the cylinder full. Move your hand over the intake port or exhaust port and listen to the change in tone to tell if its a valve leaking (they will leak a little since its metal to metal). If its rings you will hear the noise and sometimes can tell a difference in the oil dipstick.
For a bonus check. Move the piston closer to TDC and lock it in place (be careful). Then plug in the tester. If you get a different reading than before you may have an issue with the bore being out of round in which case i'd recommend an overbore to fix that problem.
Use the same amount you would use to change valve springs. 50-80psi is fine to get what you need. I try not to go over 100psi on a consistent basis.
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Post by rocketj25 on Mar 2, 2012 6:58:12 GMT -5
Thank you hammerdown. Your information was what I was looking for. Thank you again
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