I need an opinion on whether or not my test results from a Leakdown test are
valid of not. I made sure pistons were at TDC, using the scientific screwdriver
in the spark plug hole test. Does it matter if TDC is obtained on either
revolution of the engine or do I need to double check and mater sure it's truly
on TDC on the compression stroke. Here is what I came up with. Didn't have time
to run a compression check today but in the past results for one of the
cylinders were substantially below the other readings. More research to come on
this one but preliminary results are as follows.
All Tests run on 100 PSI input air pressure.
#1 90 lbs 10% Leakage Minor noise from Valve Cover gasket, no
apparent blowby
#2 70 lbs 30% Leakage Lots of air coming from #4 spark plug hole
#3 92 lbs 8% Leakage Minor noise from Valve Cover gasket, no
apparent blowby
#4 75 lbs 25% leakage Air coming from #2 Spark pluk hole,
significantly less
than test on #2.
I gave each cylinder a shot of WD-40 before performing the test.
Does the air leakage from #2 to #4 say rings bad on those 2 cylinders. Or
again is this test influenced by which part of the rotational cycle engine is
on.
Motor was described on purchase as running strong but 100 miles per qt. oil
usage with no blue smoke. I'm thinking reringing and valve job. Your thoughts?
Jim Gruber
Bugsy '68 Sprite (future Bugeye in disguise)
Cincinnati, OH
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