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1. 07:44 PM - Cowl to Spinner Fit with 2.25 Spacer (Bill Schlatterer)
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| Subject: | Cowl to Spinner Fit with 2.25 Spacer |
I have a problem with the Spinner gap caused by using the Vans 2.25 spacer
recommendation instead of waiting on the prop. First let me say that I
think the spacer method would have worked fine BUT it should have been 2
1/16 instead of 2 1/4. I am fitting a Hartzell BA to an O-360 AIA and it
just doesn't work. I used the 1/4 inch metal spacer and one washer under
the spinner plate per plans.
The first picture shows the spinner spacer which was three pieces of good
plywood cut accordingly with a couple of nickels for additional space. That
gave me a 2.230" spacer. I fitted the cowl which was a little tight at the
top and a little wide at the bottom. The faces of the top and bottom cowl
are not actually parallel. My plan was to build up the inside back of the
top cowl face and the outside of the bottom face and then shave it parallel
with the spinner plate to make a perfect 1/4. In the second picture with
no prop and spacer, the clearance at the top is a little under 1/4 and maybe
3/8 at the bottom.
Third picture. Now comes the prop and with nothing different,..the gap
closed to 0 at the top and 1/4 at the bottom. No doubt about it, the spacer
was simply too long. It should have been no more that 2 1/8 to 2 1/16 to
leave a little fill room. 2.00 might be perfect if you plan to true up the
face later. It the spacer is too long, it causes you to fit the cowl
further out from the firewall than it should be.
Here is where I would ask for an opinion on my fix.
I don't want to recut the hinges and try to move it around so I am thinking
that I will build up the top cowl face from the inside with epoxy and long
hair flox about 3/8 of an inch and then simply sand off/back 1/4 inch off
the top half of the cowl and square it up with the spinner plate. In the
third picture, you can see marks that would be a 1/4 inch gap. (effectively
just sand back to those lines)
The bottom is about right now but needs to be trued up a bit with some build
on the outside and then the whole cowl face fitted parallel to the spinner.
This doesn't seem like nearly as much work as cutting the whole face off,
trimming, and then glassing back. Other than taking a little patience, I
can't see any reason why it won't work. I don't have a lot of glass
experience yet but I think the epoxy / long hair / layer of glass on the
inside should be as strong as the original when it's sanded back a 1/4. The
last picture shows how much needs to come off on the top. ( 1/4 inch paint
paddle)
Comments please.
Thanks for any help?
Bill Schlatterer
7a ARK
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