Installing your prop?? Is there a right way?
 

Hi there,

I have a question about installing a fixed pitch prop that I am hoping someone will know the answer too.

Is there a correct way to install a fixed pitch prop in terms of orientation when cylinder no.1 is a TDC? Does it even matter?

The reason I ask is because I notice that prior to me removing my prop during the winter, it ran very smooth indeed. I then put it back on, and probably not at the same orientation to the way it was (yea, I know.. should have marked it etc..), but now I seem to have a lot more vibration.

I have double checked the bolts, hub etc.. and all is good there. Is this just because I need to get my prop and spinner dynamically balanced or is it something else? Note: It has not been dynamically balanced yet even prior to the removal.

Do I need to put the prop at say the 10/4 location, or 12/6 when at TDC no.1?

I really have no clue about this, so any expertise that is out there would be appreciated.

Just like various parts of the human anatomy, everybody has an opinion.

Check out this thread for various opinions.

http://www.vansairforce.com/communit...=prop+clocking

When addressing the "clock" position of the prop is it an industry standard to be viewing it from the cockpit or from the front of the plane.....or does it vary according to instructions from the various prop manufacturers.

I found the above thread interesting reading but very frustrating when posters gave a "clock" position, but failed to state whether the orientation was from the cabin or from the front of the aircraft.

Typically when given a prop "clock" position, it is from standing in front of the prop.

Ok good. Got that one sorted out. Now that we have a mutually accepted orientation I can ask my question.

It has been said that if the prop is installed in the 2-8 O'Clock position (when the Number 1 cylinder is at TDC) then when the engine is stopped the prop will cease movement in the 10-4 O'Clock position (ready for hand-propping).

I am imagining that the reason for this is that the prop will stop just before the engine arrives at TDC on any one piston (ie prop at 2-8 position) and will then wind backwards to the 10-4 position as the residual air compressed in the cylinder pushes the piston back down.

Is this correct.

Actually it's more like 3/9 o'clock for TDC,
 

but, yes, your reasoning is correct. With a 2-blade prop, it doesn't matter which cylinder it is. They will all stop in the same position.

prop position
 

Sensenich says if you have excessive( to you) vibration, remove prop and turn 180 deg and reinstall. I had vibration ( enough to iritate ) so I rotated the prop an it made a difference. Maybe yours is 180 deg from where it was when you removed it.