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How Much Crankshaft Drive Bushing Length?

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Feb 1, 2007
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I am in the process of fitting the spinner on my Acrosport II and I noticed that after I install the spinner backing plate, there is only about .060"-.070" of drive bushing that will protrude into the propeller when it is installed. The prop is a metal Sensenich. The engine is an O-360 A3A with an SAE #2 prop flange.

I was wondering if the bushings should protrude into the propeller further than .060"-.070".That doesn't seem like much to me, especially when you consider the chamfers that are on the end of the bushings and on the drive bushing holes in the prop.

The other part of this, is that Imight need an 1/8" spacer behind the prop for cowl clearance. If I end up needing the spacer, and I think I will, I know I will need longer drive bushings, but it would still help to know how much engagement that there needs to be.

I've tried contacting Sensenich, but I haven't got any response yet. I also tried asking this question on Lycoming news group on yahoo, and I did get an excerpt from a Sensenich prop STC forGrumman Tiger, but still not a definitive answer.

What has been the experiences of the builders that are here?

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