[Shotimes] Compression Test Results

[Kevin & Cheryl Airth]

Kevin:
 What you want is no more than 10% variation between readings. This is more
important than the actual number on the gauge. I think your compression is
just fine. The SHO sure has great ring seal from the factory!!
 If your still not sure, I would do a leak down test which is really the
test to run to check engine sealing. This test will give you a percent
reading of leak down. The lower the number the better condition your engine
is in. A race engine (fresh rebuild) might have as little as 2% leak down.
On the street anything under 10% is considered excellent.
.
.



> Here are the results of the compression test I just did:
> Before adding oil to engine:
> Cylinder 4: 195 PSI
> Cylinder 5: 195 PSI
> Cylinder 6: 200 PSI
> Cylinder 1: 190 PSI
> Cylinder 3: 195 PSI
> cylinder 2: 190 PSI
>
> After adding oil to engine:
> Cylinder 4: 235 PSI
> Cylinder 5: 220 PSI
> Cylinder 6: 225 PSI
> Cylinder 1: 223 PSI
>
> I stopped after that cylinder because I was pretty sure that the rings
were
> bad in those cylinders and that the last 2 didn't matter. Did I come to
the
> right conclusion? The Ford CD says that if compression increases
> significantly that the rings are bad, is this pressure increase
significant?
> Thanks,
> Kevin