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Bob: I would say that all the previous comments I have read are
appropriate.
I have found the tachometer readings of old, especially ones that have sat
for a considerable period of time without being used, tachometers are very
often not correct. Yours could be showing 2150, when the engine is
actually
turning 1950 RPM. When the tachometers get dry inside, they will read
different RPM if they are sitting in a position of uphill or downhill. I
recommend:
First - get the tach checked - you can do this in the aircraft if
you
have an electronic tach that uses light to read RPM.
Second - carefully check the fuel system, intake air as well as the
entire fuel delivery system to ensure there are no blockages or
restrictions.
Third - do a compression check just to see if there are any
definite
leaks i.e. out the intake (Carburetor air box), exhaust (exhaust pipe), or
past the rings (crankcase vent)
If all of these check out OK, then your problem was probably due to
the runway conditions of the day (but 2150 static RPM does not sound like
quite enough) The Coupe I just finished working on (with a fresh top
overhaul
C-85) would take off on dry grass heading up a slope in less than 500 feet
with full fuel and me (190). Its static RPM was right at 2100 with a new,
calibrated tach. When I first tried it with the old (it only had 130 hours
registered on it) tach the static rpm showed 1900 when pointed up hill and
2050 rpm when pointed down hill. It had the 71 X 50 prop and cruised at
116
mph at 2400 rpm (actual verified GPS speed, not indicated which was 3 mph
higher) And when let flat out with the windows closed, it would turn right
at
2575 RPM indicating about 128 mph on a normal day (60 degrees.sea level)
Lynn Nelsen
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