compression for a 4.2L motor ? -
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Unread 10-23-2013, 10:57 AM   #1
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1988 YJ Wrangler 
Join Date: May 2013
Location: mountain home, idaho
Posts: 51
compression for a 4.2L motor ?

I checked my compression in my 1988 4.2L engine, and all cylinders are right at 130# Can someone tell me what the optimum pressure should be so I can tell how my engines compression compares ?

Krazybob,, Mtn. Home, Idaho
My goal, is to die young,,
at a very old age
1988 YJ 4.2 5sp
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Unread 10-23-2013, 10:46 PM   #2
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1992 XJ Cherokee 
Join Date: Oct 2012
Location: umatilla, florida
Posts: 1,961
150ish on a fresh motor us good. You have great compression for an 88.
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Unread 11-16-2013, 02:17 PM   #3
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Posts: 597
The important thing with compression checks is, as in your findings, the numbers are the same across the board. That's impressive for an older engine.
A leak down test is prolly what you're looking to do to find out if the engine is tired.
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