Posted by chris case on Sunday, August 15, 2004 at 1:22PM :
In Reply to: compression anyone??? posted by adam on Sunday, August 15, 2004 at 12:05PM :
Don't try to "crank it 4 times", you don't know where it started, or ends cranking. Yours sound good, how does it run? If it runs well, no problem, record your findings for future reference.
I do a 'cranking balance test' first. Just unplug the coil, crank while listening for rhythm. No rhythm, all OK. You can hear a 5 psi variation, which is negligible, but if so, proceed to a DRY compression test. Usually 20% variation is OK- you have 17%, probably OK. Possibly carbon raising compression in high holes. Burned valves lose LOTS of pressure fast. Wet tests seldom prove anything. Too much variation in the amount of oil injected, how long it sits in each hole, carbon deposits, etc. If you have low compression due to bad rings, you will have blowby allover the place.
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