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Re: Compression 150, 90, 75, 150 ....question (archive)

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Posted by rjb on June 25, 2001 at 18:28:06:

In Reply to: Compression 150, 90, 75, 150 ....question posted by Warren, Australia on June 25, 2001 at 17:57:23:

I used to check comp first without oil the hole and then again with a shot of oil in each cyl. If compression was appreciably higher with the oil, then the rings are suspect, if no difference between oil and no oil, probably valves. I would guess you might need some valve work or a head gasket. Also, taking plugs out of a hot aluminum head can cause additional sadness. Also bad is that both interior cyl are low. Adjacent low compression can be head gasket. Hope it isn't cracked or corroded - could be as simple as a bad head gasket between 2 & 3. Ever notice cooling system pressure when first started(cold)- can be hd gasket. Hope this helps

... on a warmed-up open-throttle plugless engine. And besides being a daily driver with no oil loss, according to MacCartney these engines shouldn't work with a compression less than 100 PSI!

After a squirt of oil into the combust' chamber, pressures are 150, 95, 80, 150.

-leaking valves, leaking bores?

-Guess I'm looking at both a head and block rebuild.

-I'm thinking about just a head rebuild but am I wasting my time?


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