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David Burke

Member
I am awaiting the delivery of the prop - can I use 2 1/4 spacers to fit the spinner backplate while I wait for the prop to start the cowl fit? Does the spacer sandwich the backplate between it and the prop ?
 
Fitting Cowel

Catto cut my spinner and fit it to the rear bulkhead. The spinner overhangs the rear bulkhead about 1/8 inch. I think this is common.










Bruce 9A
 
I used Van's measurements to the "T". Cut the blocks out of hard wood, remeasured three times. Allowed for Sag. End result. Cowling was too tight. I am now having to remove hinges from the rear to cut about 1/4" inch off the rear. I thought I had this cowl fitting so well. NOT. Best advice don't fit your cowl until you have the prop on it.
 
Van's Lies

Again, again, again! Gad, I really wish Van's would correct wrong information. This keeps cropping up.

It may well be the same for Sensenich with the hub extension, but for the benefit of Hartzell installers, the correct length is 2 1/8, NOT 2 1/4 for the simulating spacers. Study the drawing, note (for a CS at least) that a 1/16 washer in addition to the Hartzell-supplied 1/4 spacers is required for blade-to-backplate clearance in full high pitch, then do the math. Trust Van's and you loose 1/8 inch - 50% of your gap if targeting 1/4 - between spinner and cowl.

John Siebold
Boise, ID
 
John, finally someone makes some sense about the spacer "spacing". Now I can see why it might not work. In looking at the prints, I see the washer (1/16) but why do you say it's a full 1/8 off. I only see one washer,... are you adding the spinner plate thickness as well?

Thanks Bill S
7a Ark finishing
cowl fitted with 2.25 spacer and no prop ;-(
 
Bill,

The information lacking is the distance from the seating surface on the crank flange to the seating surface on the prop hug that the bushings sit on. Van's doesn't show this in drawing C4, I'd guess because they don't want to be responsible for a measurement controlled by Hartzell. But really, folks, the game's exposed by Van's suggesting the 2 1/4 spacer (which is wrong!).

That secret dimension is 2.500 inches.

Prop hub "secret dimension": 2.500
Hartzell supplied bushing: ( .250)
Added AN960 washer: ( .062)
Spinner backplate thickness: ( .062)
_______
Flange-to-backplate spacer: 2.125

If instead of 2.125 (2 1/8) you followed Van's 2 1/4, the cowl is chasing the too long spacer forward. Then, along comes the prop that needed 2 1/8 for simulation, and you loose 1/8 of the gap you set.

John Siebold
Boise, ID
 
After having to remove the back hinges, I am not shooting for 1/4" any longer, if it winds up to be 1/2" so be it. Using Van's measurement and coming up too tight, really miffs me. The cowl as I had it set using their blocks was perfect, took a lot of time and now back to square 1. To be honest, I have received better help & advice on this site. When you call Van's most of the time it seems they instantly are on the defensive and in most cases talk to you like you know nothing or this is the first time this question has ever come up. I quit calling. Better to ask you guys, most are very helpful and have always solved any question I had.
 
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