Valves and Compression

[james accordino]

Cool.  Thanks for responding.
--- SJ <syljay at optonline.net> wrote:
> Here is the article I wrote on making your own leak
> down tester.
> SJ

Agreed on the tolerance.  Anybody else?  I think you'd
need a broken valve spring or more than 1 on a
multi-spring deal to hang a valve.  Obviously, less
leakage is  better, but I think 10-15% is reasonable.
Time also plays a factor.  How long are your
observation times?

> and will tell you how much leakage exists. 5% is ok
> . . .. 20% is bad.
> Got a bad leak?  Listen for it. . hissing in the
> crackcase breather means
> bad rings . . . hissing in exhaust means bad exhaust
> valve . . . .hissing in
> manifold means bad intake valve. Intermittant
> readings? . . sticky valves.
>
> "Case 1--The spark plug fitting is sitting in free
> air. there is no
> resistance to the flow of air and the gauge reads 0
> psi. You might actually
> see this reading with a holed piston or a split
> valve head."
>
NEVER.

> "Case 2--The spark plug fitting is closed off with
> an extremely
> tight-fitting cap. Since there is no flow through
> the orifice, the is no
> pressure drop and the gauge will read whatever the
> inlet pressure is,
> *exactly*. You will never see this reading in real
> life but you may get
> close with a newly assembled racing engine built to
> close tolerance."

Thanks
Jim Accordino


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