 Compression Test Results, Need 2.0 Compression Service Limit |
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| Brinks |
 May 10 2009, 08:13 AM
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#1
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Newbie  Group: Members Posts: 2 Joined: 10-May 09 From: Jersey Shore Member No.: 10,349 Region Association: North East States  |
Can somone verify the expected compression test result for a stock '76 2.0 with a 7.6 compression ratio? Also, what would the lower service limit be before considering a rebuild? Thanks...
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Replies(1 - 8)
| Cap'n Krusty |
May 10 2009, 08:24 AM
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#2
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Cap'n Krusty Group: Members Posts: 10,794 Joined: 24-June 04 From: Santa Maria, CA Member No.: 2,246 Region Association: Central California |
I like to see 125. Any variation of 10% or an average of under 100 is not good. Always do the test hot with a fully charged Battery and all the spark plugs removed. It's a good habit to hold the throttle wide open, but not exactly necessary in this case, as you have a common plenum with D-jet.
The Cap'n |
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| Cap'n Krusty |
May 10 2009, 08:25 AM
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#3
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Cap'n Krusty Group: Members Posts: 10,794 Joined: 24-June 04 From: Santa Maria, CA Member No.: 2,246 Region Association: Central California |
Accidental double post ........
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| sean_v8_914 |
May 10 2009, 11:29 AM
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#4
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Chingon 601 Group: Members Posts: 4,011 Joined: 1-February 05 From: San Diego Member No.: 3,541 |
they shold all be within 10% as stated above. if they are well worn together...say 90psi, it will still run OK but shes tired
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| Jake Raby |
May 10 2009, 11:59 AM
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#5
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Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
Numbers will vary due to the elevation you are testing at, if the throttle is open or close fully as well as engine temperature.
What matters most to me is that the cylinders test within 10% of each other. Here at my elevation a bone stock engine in good shape will generally have about 110 PSI per cylinder with the engine cold. |
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| tod914 |
May 10 2009, 02:34 PM
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#6
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Advanced Member Group: Members Posts: 3,755 Joined: 19-January 03 From: Lincoln Park, NJ Member No.: 170 |
I had a shop do mine on the 75 several years ago before sale. The numbers they were comming up with were around 65 + or - 10%, yet it showed an excellent leak down. I asked them how it could run with that kind of compression. I went out and purchased a compression tester from sears. Did the engine cold with all plugs out and throttle wide open.
Results went up to 140. I suspect the throttle body was closed when they did it. |
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| Cap'n Krusty |
May 10 2009, 02:41 PM
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#7
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Cap'n Krusty Group: Members Posts: 10,794 Joined: 24-June 04 From: Santa Maria, CA Member No.: 2,246 Region Association: Central California |
On a car with a plenum serving all cylinders, it doesn't matter much whether the throttle is open or not.
The Cap'n |
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| Brinks |
May 12 2009, 02:39 PM
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#8
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Newbie Group: Members Posts: 2 Joined: 10-May 09 From: Jersey Shore Member No.: 10,349 Region Association: North East States |
One last bit of info:
The seller states: "All are within spec. Brand new they should be about 105psi. These are all in the mid 90's except number 2 which came in at 92." So how much life is left in this engine? In your opinion, is this 2.0 a candidate for rebuild? Top end/bottom end, or both? |
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| Cap'n Krusty |
May 12 2009, 02:45 PM
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#9
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Cap'n Krusty Group: Members Posts: 10,794 Joined: 24-June 04 From: Santa Maria, CA Member No.: 2,246 Region Association: Central California |
Without a retest using a known good compression tester, I'd shy away from this one unless it's too good a deal to pass up. Mid 90s is scary, and 105 IS NOT what it should be.
The Cap'n |
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