sticky valve or

Dick wrote:
snip
Light Plane Maintenance book references "hand proping before first
start of
day to find 'flat' cylinder". Not sure I can identify a rapid falloff
in
turning resistance (books definition).

I think you can. It should be pretty straight forward. As you
rotate the prop you can feel the resistance from each cylinder on the
compression stroke. If you hit a cyl. with a stuck valve, you'll
notice the difference in resistance right away. If it's quiet, you
should also hear hissing at the exhaust pipe if it's an exhaust valve.


John Galban=====N4BQ (PA28-180)

Two of us tried the "armstrong method" (rotating by hand) yesterday and both
thought we got very slightly lower resistance, but on different cylinders on
opposite sides of the engine. Him #1 and me #2 &#4..

Decided to do a "differential test" with the engine cold, rather than warmed
up. Our thought being that any matter between seat and valve would
indicate a lower reading.

Observed 78/80 on three and 77/80 on the fourth. For last 5 years the
readings have been in the 76-78 over 80 psi range.

Don't know if it matters in my case, but realize now that I've never
listened for any leaks.

My helper did mention that he thought the leakdown period should be about 5
minutes instead of just holding 80 psi long enough to observe where
indicator stops...

Thanks, Dick

ps Glad to hear that 11-1200 rpm hesitation is normal.

They call that the "Continental cough"...My A-65 doesn't do it, my dad's
C-85 doesn't do it, but my old C-85 on my Chief did. Don't think that
is worth worrying about...

Scott
http://corbenflyer.tripod.com


Dick wrote:

Two of us tried the "armstrong method" (rotating by hand) yesterday and both
thought we got very slightly lower resistance, but on different cylinders on
opposite sides of the engine. Him #1 and me #2 &#4..

Decided to do a "differential test" with the engine cold, rather than warmed
up. Our thought being that any matter between seat and valve would
indicate a lower reading.

Observed 78/80 on three and 77/80 on the fourth. For last 5 years the
readings have been in the 76-78 over 80 psi range.

Don't know if it matters in my case, but realize now that I've never
listened for any leaks.

My helper did mention that he thought the leakdown period should be about 5
minutes instead of just holding 80 psi long enough to observe where
indicator stops...

Thanks, Dick

ps Glad to hear that 11-1200 rpm hesitation is normal.