Prop Pitch !! Help

[16Pilot]

Is it going to affect me in a negative or positive way going from a 8 1/4x8 to a 8 1/4x9 on a 12ft fiberglass ? and is ok for the motor ?<br />it is a 1970 9.5hp (runs great except for the coughing at idle)

 

[Walker]

Re: Prop Pitch !! Help

No way we can say. If you are under-propped now, then it may be a slight improvement. There is very little difference in the 2 props. If your are propped just right or over-propped now, then you will lose some performance. Your coughing at idle is caused by running lean. try adjusting your idle needle out some.

 

[16Pilot]

Re: Prop Pitch !! Help

Thanks walker, it seems like no matter how much I enrich the idle it still coughs every 20 seconds or so. I think maybe its an exaust leak.

 

[Jack Shellac]

Re: Prop Pitch !! Help

Well, you really need a tachometer to tell if it's hurting or helping. The motor should run in the upper 1/4 of the WOT RPM range if it's propped right. Otherwise, we're just guessing.

 

[16Pilot]

Re: Prop Pitch !! Help

I took my prop off yesterday because I sheared pin. It is actually a 8 x 7. The service manual says 8 1/4x8 I just ordered a 8 1/4x9 because I got it brand new for $26.00 and Its a $100.00 prop.