"Paul Millner" wrote in message ...
Well, that's really not evident from the data you shared... maybe it was
flying 500 hours/year before you bought it? But compressions only tell you
about the top of the engine. Is there any valve train wear, are you still
getting full horsepower, or have the tappets worn so you're not getting full
valve lift? Do you really want to run the engine until the $5,000
crankshaft starts machining its way through the main bearing backing plates,
turning it into junk?

These are imponderables, perhaps, but saying, "the compressions are good so
I'm going to keep on flying" ignores some major factors in economic
ownership.

Figuring he is the expert, who am I to question.

Well, you're paying the bills not him, and it's your butt in the air, not
his... and who's pilot in command, anyway? :-)

Paul

The Type Certificate Data Sheets will give minimum and maximum
static full-throttle RPMs for that engine/prop combination in that
airplane, and if there is valve train wear the RPM will be out of the
range. This isn't rocket science. If the crank is eating its way into
something, there'll be metal in the filter. That's simple enough, too.
If the oil pressure is well into the green, and doesn't drop to zero
at idle when hot, the bearings are OK. If the compressions are as high
as he's indicated, there isn't much wrong with the top end of the
engine, other than perhaps corroded valve stems.
Lycomings have been known to swallow valves when the head broke
off the stem because of corrosion pitting in engines that have been
run for short periods and left to sit. Similarly, the crankshafts in
these engines build up water/oil sludge in the crank nose (unless it's
driving a constant-speed prop) and this causes dangerous corrosion
that can result in propeller departure.
Lycomings run regularly on long flights have reached 4000 hours
without overhauls.
Tell me what airplane it's in and I'll look up the prop RPM range
for you.

Dan