Thread: compression checks

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advise pleese i took a compression test because my motor just wasn't right and got not so good numbers

cylinder 1,2,3,6,7 were all in the 130 to 140 range witch i think is good but 4 was 90 5 was 80 and 8 was 20 and advice to what i need to do to get it runnign right its a stock 360

Originally posted by pauly_wheels
advise pleese i took a compression test because my motor just wasn't right and got not so good numbers

cylinder 1,2,3,6,7 were all in the 130 to 140 range witch i think is good but 4 was 90 5 was 80 and 8 was 20 and advice to what i need to do to get it runnign right its a stock 360

you need to do a wet test now. shot a little oil in the cylenders thats low and if they stay the same then you have a valve problem, if the pressure increase then the rings are bad, find out which one is bad then you can decide what to do.

Originally posted by techinspector1
It's been my experience that even if you found out it's the valves and did a valve job and bolted the heads back on, it wouldn't be long before the newfound compression would blow the rings out of it. May as well figure on a complete rebuild.

i agree, but there is a lot of head gaskets and valve jobs being done every day out here in the repair shops. everybody dont have 2000.00 for a motor right now i guess a lot of them dont have the 400.00 for the valve job.

if you goto the right machine shops, a valve job can be $75 if you pull the heads and they can just regrind the valves, if you hafta buy new valves, you might be lookin to about $175