> Cyl #1 - Compression 190 dry, 220 wet, leakdown 5% dry, 5% wet
>
> Cyl #4 - Compression 190 dry, 215 wet, leakdown 4% dry, 4% wet.
>
> I'd never try this on my street TR6 because it runs great and I don't
> want to know anything else.
>
> The differences are tiny, but it might be interesting to try to
> diagnose the little bit of leakage there is. To me, all this says
> that cyl #4 is tighter than cyl #1, and the little bit of leakage
> there is appears to be at the rings. Maybe. Or just maybe the
> indexing of the camshaft lobes by the cam grinder is just a little
> bit different for #1 and #4, because overlap also influences the
> compression gauge reading, right? Unless somebody has a correct idea
> instead of this one.
Interesting that the 'wet' compression reading was less in #4, even though
the leakdown tester showed less leakage. One explanation for that might be
that you got just a little bit more oil into #1 than into #4, since the
extra oil has the effect of raising the compression ratio during the test.
Adding oil will always raise the reading somewhat, for that reason.
In any case, I would certainly believe the leakdown tester over the
compression gauge.
Randall
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