Compression Test, How are these Numbers?

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Sep 20, 2006 | 10:14 PM

Jansenwins

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From: Bettendor Iowa

Compression Test, How are these Numbers?

85 L98 with original shortblock. I swapped heads for some 64 cc edelbrocks. The shortblock has 121K on it. I did a compression test on each cylinder and got the following numbers:

1 - 204 2 - 202
3 - 214 4 - 211
5 - 201 6 - 204
7 - 212 8 - 210

The engine was warmed up to operating temp, and the throttle was held wide open. I gave each cylinder 5 rotations to achieve max compression.

How are these compression numbers?

Sep 20, 2006 | 10:32 PM

Pete K

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They look just fine to me

Sep 20, 2006 | 10:33 PM

mackeyred96

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From: Former NCM Drag Racing coordinator, National director Corvette Challenge Spring Hill, Tennessee: Whiting, New Jersey

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They look fine

Sep 20, 2006 | 11:02 PM

Jansenwins

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From: Bettendor Iowa

Quote:

Originally Posted by Pete K

They look just fine to me

OK, Thanks! I was thinking that my rings must be worn out (considering the mileage), and considering making a shortblock freshen as my winter project. These numbers looked good to me but I am no expert. I'm thinking my rings are rock solid (knocking on wood).

Thanks again.

Sep 21, 2006 | 03:01 AM

JLeatherman

Burning Brakes

Joined: Sep 2006

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From: MD

My 84 with pretty low mileage that sat around a lot before I got it is pulling 110-120 on 5 cylinders. I wish I had your numbers. It's rebuild time for me.

Sep 21, 2006 | 04:26 AM

comp

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From: eville in

looks like rings and valve seats are OK

Sep 21, 2006 | 08:28 AM

IRAraid

Racer

Joined: Jun 2006

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From: Elkton MD

Compression Numbers

Jansenwins, the compression looks fine. How's your oil consumption? If it's good (low), valve guides/seals must be OK too.
Aside to JLeatherman: Drive it around for several tanks of gas. You might get a pleasant surprise. I've stored cars for a number of years and found that when first back on the road they smoked (blue oil fumes) for a few hundred miles then recovered very well (compression and oil consumption-wise). No smoke now either. (Didn't mean to hijack the thread.)

Sep 21, 2006 | 11:00 AM

Jansenwins

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From: Bettendor Iowa

Quote:

Originally Posted by comp

looks like rings and valve seats are OK

Heads are new so I figured this test would tell me how my piston rings are. The engine is not using oil....but, unfortunately it has a leak. Drips off the bottom of the bell housing, oil filter and gets on the drivers side collector. Been chasing it and can't find the start point of the leak.....