>old Motor's Auto Repair Manual for the specs on a 1950s
>L-head 134 Jeep engine with 6.48:1 compression ratio,
>and it said that 100 pounds compression is normal.
One guy up the street who was familiar with this engine as a teenager years
ago thinks 100 was typical when he worked on them.
>some carbon debris will ALWAYS fall down onto the piston
>and valves. Even a tiny amount of this crud will hold a
>valve open just slightly...It's always a good idea to loosen the
>spark plugs about a turn and a half and let the engine idle
>for a minute or two.
The flat head design will even allow *external* junk (dirt, paint flakes,
etc) to easily fall in the hole if you're not careful. I blew out the
depressions around the plugs with canned air and probably took care of the
outside stuff but I couldn't do much about the stuff on the inside.
Running the engine... that brings up another point: I made my readings with
the engine dead cold. In fact, it had not run for a week or so. Perhaps
that would bias the readings one way or the other.
> cranking speed can make a significant difference.
Well, I can't say the starter is a real cranker -- it spins it at a fairly
slow rate, ruh, ruh, ruh.
>Just guessing, I'd say your compression is probably OK.
Thanks for the tips, Alan. Even if the compression isn't quite up to spec,
at least there is not an obvious defect in one or more cylinders.
Steve Johnston
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