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Posted by john
on 8/29/2009, 6:34 pm, in reply to "Re: Compression"
71.199.16.246
Those are okay numbers for a car of that age. Mine are somewhere in that range as well.
Very important is the fact that they are all pretty much the same. That means that your engine is wearing down "evenly" as opposed to a burned valve, or broken rings. It starts out nice and high, and as things wear, compression goes down. Hopefully, equally, as yours seem to be doing.
Did you test hot or cold, and did you hold the throttle open while cranking, with all the plugs out at the same time?
I looked in my GM shop manual but couldn't find the percentage difference that is considered allowable. Maybe someone else has that number, but based on your readings, all is well.
Not much you can do about a lean burning cylinder. If it runs smooth, passes any emissions test if you need them, drive on, and have fun :-)
John
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