Stealth Pilot wrote:
: your prop has 6 bolts. all symetrical. the prop can sit in many
: positions relative to the piston positions.

: I remember a thread about a dozen years ago where the prop position
: was found to have a noticeable effect on the power out of the engine.
: something to do with the coinciding of the blade wash across the inlet
: at the time of air suck. (substitute your own technical terms)

: you look to be heading to my sort of insanity (my carby fix took 18
: months and $2,500 but by hell I understand the bugger now)
: comiserations!

: try changing your prop position relative to the crank. a spool of
: lockwire and some lockwire pliers should be cheaper than $600.

: Stealth Pilot

Good thought, although I'm not sure that I buy into the propwash making pulsating
ram air. In any event, we re-indexed the prop awhile back and it made no effect on either
vibration or power output. The irritating thing is that the PA28 service manual specifies
the prop indexing in an ambiguous way. It says to put it on at 2 o-clock and 8 o-clock
at TDC. That's not an option though... the 6-holes line up at either the 12-6 or 10-4
position. Either position is halfway incorrect (but we've done both to no effect). Even
if it did have an effect, it would show up as an increase in manifold pressure.

Thanks for playing.... Welcome to my hell.

-Cory

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************************************************** ***********************
* Cory Papenfuss, Ph.D. Electrical Engineering, PPSEL-IA *
* Research Associate, Vibrations and Acoustics Laboratory *
* Mechanical Engineering *
* Virginia Polytechnic Institute and State University *
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