We indexed our new prop horizontally according to these instructions;
I think I actually read the same information on some type of Sensenich or Lycoming document, but I can't find it again right now.
Our prop stops vertically 95% of the time. Occasionally, however, it will stop horizontally for some reason. The engine and prop are both very smooth with this configuration, and the position for hand propping is about right.
On our Twin Comanche (IO-320 engines), the props are indexed just like the ring gear on the engine; you can only install it one way. They both stop at about 10/4 to 11/5 position (viewed from seat). Hand propping is very hard, though, because it fires about 30° past vertical.
http://www.shortwingpipers.org/forum...light=indexing
"Hey, that did't take long.... I found the indexing info in the SWPC useful info. Here it is.
Propeller Installation on ShortWingPipers
Remove #1 spark plug. Rotate crankshaft till pressure begins to build
(place thumb in spark plug hole to feel/hear pressure building).
You are coming up on TDC for #1 cylinder. Continue rotating crankshaft
until #1 piston is TDC (use timing mark on back of ring gear aligned
with crankcase split or use markings on front of ring gear aligned
with punched hole in starter housing).
With #1 cylinder on TDC, the prop should be installed such that it is
Horizontal, ie level to the ground.
There should be a small "no 1" stamped near the hub on one prop blade.
That blade goes "over"/"toward" the No. 1 cylinder. It is permissible
to install the prop "180° out", but only as a "fix" for a SLIGHT vibration
at cruise. Nine times out of ten, it will NOT be an issue. Torque prop
correctly (visit Sensenich's website for detailed instructions or see pdf
file on this site) and safetie prop bolts, reinstall spinner and spark plug.
Button up airplane. Your prop will now be in the PROPER position not only
for handpropping, but more importantly will also be "timed" to best act as
a "flywheel" with the crankshaft.
Don't forget that this is not Preventative Maintenance, and requires
a Logbook entry by an appropriately rated Mechanic. "