************
Hi Steve,
There are several things you could consider:
First of all, I've found is that compression specs will vary, depending
on the source. For example, I just checked an 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.
They did not give a maximum value. They also indicated that anything
within about 20 lbs of that is normal (to me, this is kind of a wide
range...I'd say anything within 10-12 pounds.
Second, when you pull the plugs out to check the compression, 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...enough
to lose several PSI. 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.
Then remove the plugs and crank the engine for at least 30 seconds
before taking a compression reading, and even then, there's no guarantee
that you got all the crud off the valve face surfaces.
Third, cranking speed can make a significant difference. The compression
specs are based on a starter motor in good condition and a battery that
is fully charged, and good starter drive gears, etc.
So, try it again and see what you get.
Here's another little trick. IF it turns out that the compression is
below normal, pour about a teaspoon of motor oil down a spark plug hole
and do another compression test. If the compression rises significantly,
but it is still below normal, it suggests that rings are the probable
culprit. If the compression does not rise significantly, it suggests
leaky valves.
Just guessing, I'd say your compression is probably OK.
Alan
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