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Prop Clock with spacer question

bret

bret

Well Known Member
The original thread has a lot of info but my question concerns the Saber spacer, my engine came off a Mooney, IO360 A1A, they do clock the blades with the #1 crank throw, but with the spacer, the mounting holes for the crank and prop are not in alignment, they are in between each other, so do I advance or retard the prop blades? or does it mater?
 
Clocking with spacer

Hi Bret,

I had the same dilemma with a Hartzell CS and a 2.25" spacer for a James cowl. I ended up advancing it a half space. I then did careful dynamic prop balancing. The propeller stops after running exactly horizontal. Fairly minimal vibration through the normal operating ranges. There is no science in my approach but it seems to be working just fine. About 30 hours so far.
 
Thanks for your input, have you done engine off glide testing? I am concerned with the prop horizontal and disrupting the airflow over the wings, or should I not get in this predicament and keep the prop wind milling incase of engine out?
 
bret said:
Thanks for your input, have you done engine off glide testing? I am concerned with the prop horizontal and disrupting the airflow over the wings, or should I not get in this predicament and keep the prop wind milling incase of engine out?
Click to expand...

The glide testing is a whole other topic worth investigating. Based on reading, I would not expect to stop the prop, the engine might start again, and if over certain speeds will begin to rotate again anyway. I plan to just do the testing for a better personal understanding. I clocked my prop like Mr Wynn. No special reason, just the minimum rotation from standard.
 
+1 for curiosity here. Have not flow yet, but I clocked mine one space ahead. Id love to play with some different clocking with some balance data. Some previous reading suggests it could improve vibration characteristics.

Caleb
 
I have my Catto set sett stop horizontally. The reason is simple, years ago I was taught to always park planes with wood props horizontally because the prop could absorb moisture and the lower blade getting heavier, throwing the balance off.

With the prop stopping horizontal, I don't have to move the prop by hand, risking an accidental firing of an ignition and subsequent prop strike to my hand.
 
Catto horizontal, how Bill ?

my Catto will not clock in line with the crank at TDC. The Saber spacer is drilled for the Lyc flange. Therefore, the prop bolts are between the spacer/flange bolts.
The Catto prp is apparenty drilled to match the Lyc flange with 2 blade prop able to align with the crank. Therfore my prop can never be closer than +_ 30 degree.Catto says it doesn't matter, no harmonics to fear !!!

If I am missing something, please comment. I plan to balance soon..Larry
 
N941WR said:
I have my Catto set sett stop horizontally. The reason is simple, years ago I was taught to always park planes with wood props horizontally because the prop could absorb moisture and the lower blade getting heavier, throwing the balance off.

With the prop stopping horizontal, I don't have to move the prop by hand, risking an accidental firing of an ignition and subsequent prop strike to my hand.
Click to expand...
Yeah, good call. Another reason is preventing a possible prop strike in an engine-out scenario and off-airport landing. Sure, the prop is the least of your concerns in this situation, but if you do manage a cushy landing, it's one less piece to replace.
 
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