> ...The only thing I can think of is that the
> piston isn't moving (yikes)?
I would think that there would be some other pretty bad noises
if something was broken/disconnected to this extent. But it's
easy to tell. Just shine a light down the sparkplug hole and
turn the engine a quarter turn. Look again and the piston
should have moved. You can see the crown when it's any where
Somewhere your compression tester has a one-way valve. I am
guessing that you are trying to blow against that valve and
that's why it seems solid. You won't be able to suck against
the valve either (and besides, you don't want a mouth full
of engine fumes.
Try using an air compressor blow gun (set to 10-20 psi) with
the rubber tip (press it into the spark plug hole), or a piece
of heater hose pressed tightly against the head. I bet you can
blow air thru that way.
You may have dropped a valve seat if you're lucky. Measure
the total travel of the valve stems, and compare to another
cylinder. A stuck-open valve won't move nearly as far. If
the valves are marginally working, my next guess is that
you've got a hole in the piston (or burned the side of the
piston off - I've seen that problem up close and personal).
With air being blown in and the engine turned so both valves
appear closed, listen at the carbs for hissing (open intake),
the PCV pickup on the valve cover (fried piston), and the
exhaust pipe (open exhaust).
I'm betting on a dropped seat.
John F Sandhoff firstname.lastname@example.org Sacramento, CA