You could be right. The compression gauge is the rubber tipped kind
that you force into the spark plug socket. There is plenty of room for
user error. At least one cylinder had just under 100. They're not all
exactly the same, just fairly low.
I just did a valve job (about 20 minutes before I measured the
compression), so that shouldn't be a problem. It made an improvement,
but I'm not sure how much power this engine should have. It's the only
one I've driven. It seems to have plenty of pickup for a 1500, but then
again, no reference point.
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From: Denise Thorpe[SMTP:thorpe@kegs.saic.com]
Sent: Tuesday, October 03, 1995 6:07 PM
To: mroach@socketis.net
Subject: Re: '75 Midget Engine Rebuild
> Randy mentioned in an email to me that 75 psi was rather low for an =
> Midget. He also mentioned that rebuild was likely necessary (rings, =
> head gasket, etc. could be the culprit).
>
> I plan to replace the head gasket within the next couple of weeks. I =
> figure I can do that without tearing the entire engine out. Hopefully, =
> it won't take longer than a day. Also, I have an engine rebuild planned =
> already (along with a carb (tons of vacuum leaks) and front end (new =
> shocks and king pin cleanup) rebuild) for this winter. I hope to drive =
> it until it gets too cold, then disassemble her.
>
> My question is: is there a problem with running the engine with a bunch =
> of vacuum leaks and low compression?
>
> j. michael
I can't believe a Midget with only 75 lbs runs very well at all, but it
won't hurt it to run it with low compression. However, running a car
that's running too lean (vacuum leaks) will burn valves.
The fact that all of the cylinders have the same low reading makes me
suspicious. Engines don't generally wear out the rings at exactly the
same rate. And head gaskets generally blow between two cylinders so that
only two cylinders are low. Since your car still runs, I'd suspect your
compression guage. If the compression is really that low, it would be
more likely to be something that affects all of the cylinders equally like
the timing chain. Or maybe the valve lash is adjusted too tight on all
valves. A valve problem would explain your vacuum leaks too. If I were
you, I'd look into it more before tearing the engine apart.
Denise Thorpe
thorpe@kegs.saic.com
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