At 10:10 AM 4/7/95, jpratchi wrote:
>2) What is healthy compression? I have 110,105,125,110,105,125 for 1-6
>respectively.
>
>At 14.7 lb/sq. in., these equate to compression ratios of just over 7.1 :1
>to 8.5 : 1. The cylinders with 105 and 110 may have some valve seat leakage,
>valve lash maladjustment or some ring blow-by. I think the 8.5 : 1 is pretty
>close to the correct value for this model year.
>
As nice as it may seem to do this calculation, it just plain isn't
accurate. It ignores several factors, the most important of which is the
heating of the air being compressed. The only way to actually compute the
compression ratio is by measuring the volumes.
That being said, I think you're in OK shape. You can find out what is
leaking with a leakdown tester (make it yourself or get a good deal on one
from Aircraft Spruce). You can also try the quick and dirty test for rings
- put about a tablespoon of oil down the spark plug hole and see if the
number improves.
(Have you adjusted your valves lately?)
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