Jim---The low compression on one cylinder is either from a valve not
seating on your #6, or the piston could have a broken ring land. The
usual "test" of squirting a teaspoon of oil into this sparkplug hole may
not work, as it would if there were only worn rings. Give it a try,
anyhow. If the compression doesn't come up 20lb. or so, it's probably
one of the valves on this cylinder. Be sure there's some lash here, as
no lash = compression loss, as the valve isn't seating.
It isn't normal for one cylinder to drop this much more than the others
due to just general wear, tho the engine can appear to run fine this
way.
Dick T.
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