Compression test numbers

Rick 91GT · 03-02-2001, 03:52 PM

Did you put a tsp of oil in each cylinder turn the motor over and the re-run the test? That will tell you if it is your rings or heads. I think 120 is a little low but it is with in range, 130-150 is more optimum.

I just did mine I had

180
185
180
175

180
110
170
100

I was really happy with my results except for those two low readings. After I did the test and re-ran it with oil it didn't change, so I know my rings were OK. I pulled the heads off and found I had bad valve seals and guides. Cylinder #8 which read 100 the valve seal was gone and a piece of it was stuck in my drain hole in the back of the head. The seal from #6 was stuck up out of it's seat in the retainer. Holley is sending me new ones no questions asked....they have had a rash of problems a rise with bad valve guides and seals.

If your compression goes up after adding the oil it is the rings, if it doesn't change then it is in the heads.
Hope this helps

------------------
My Ride Check Out My Site 91GT, Holley SysteMAX II Kit-Heads 2.02" x 1.60",Full MAC exhaust 1-5/8" Long tubes, 2-1/2" O.R H-Pipe, 2 1/2" cat back, 12" K&N Filter, RNH PERFORMANCE Ram Air, Ron Davis Radiator, Full Suspension,3:73's, Welds, Best on new motor-12.60 @ 108, no traction 1.98

[This message has been edited by Rick 91GT (edited 03-02-2001).]

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03-02-2001, 03:52 PM	#2
Rick 91GT Procharged! Join Date: May 1999 Location: Hanover, PA Posts: 1,539	Did you put a tsp of oil in each cylinder turn the motor over and the re-run the test? That will tell you if it is your rings or heads. I think 120 is a little low but it is with in range, 130-150 is more optimum. I just did mine I had 180 185 180 175 180 110 170 100 I was really happy with my results except for those two low readings. After I did the test and re-ran it with oil it didn't change, so I know my rings were OK. I pulled the heads off and found I had bad valve seals and guides. Cylinder #8 which read 100 the valve seal was gone and a piece of it was stuck in my drain hole in the back of the head. The seal from #6 was stuck up out of it's seat in the retainer. Holley is sending me new ones no questions asked....they have had a rash of problems a rise with bad valve guides and seals. If your compression goes up after adding the oil it is the rings, if it doesn't change then it is in the heads. Hope this helps ------------------ My Ride Check Out My Site 91GT, Holley SysteMAX II Kit-Heads 2.02" x 1.60",Full MAC exhaust 1-5/8" Long tubes, 2-1/2" O.R H-Pipe, 2 1/2" cat back, 12" K&N Filter, RNH PERFORMANCE Ram Air, Ron Davis Radiator, Full Suspension,3:73's, Welds, Best on new motor-12.60 @ 108, no traction 1.98 [This message has been edited by Rick 91GT (edited 03-02-2001).]