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Mounting the SJ cowl

D

Darren S

Well Known Member
I'm finishing up the "pre-engine mount" firewall penetrations ie. Battery box, Solenoids, transducer etc....

I read somewhere that I should think about fabricating and mounting an aluminum strip that mounts between the firewall and the side skins. This strip will hold the camlocks that will eventually hold the SJ cowl on. I don't have the SJ cowl yet, I'm on the waiting list.

How do I best approach this fabrication ? Mock it up in thin cardboard ? Is there a template somewhere ?, what about Camlock spacing ? Anybody got a good pict :)

Thanks,

Darren
 
Right, plan it now.

Absolutely, plan it now. Plan how thick a flange you will need. Plan for it over the top of the firewall, too, not only the sides. I did it on the bottom as well. I have only Milspec camlocks around the aft end of the cowl, but used hinge for the horizontal joint between the two portions. IMHO it was a good decision.

The piece that goes over the top is curved and will require some shaping and/or flange-tool adjustment. .040 minimum thickness, though.

Spacing is optional. I ordered extra pieces from Milspec in order to get the spacing I wanted. Keep in mind where the cowl joint is because you will want to be fairly near the corners, so closer together there than, say, down the sides. I used 3 on each side of the bottom.

I can email you some pics if you supply an email destination.
 
I decided to skip the AL strips until I had the cowl available for proper spacing. then Fab'd the strips and shims to fit. The only problem with this method is riveting everything in place. Not too fear, pulling the engine mount with everything hanging on it is easy!

Here's the Engine pulling link
 
Hope this idea helps!!

Given this is our second RV project, we're trying to improve on all of the issues we had with #1. One concept I'd like to suggest is "registering" the cowl to the engine so that every time you mount the cowl during fabrication of the hinges (etc), it goes on the exact same place. That way you're not working with a moving target as you attempt to install hinges.

Here's how we did it. We built the O-360 engine but did not install the jugs, mags or anything else not needed. That way we had lots of clearance and good visibility. Chet (an experienced wood worker) built a front spacer that's exactly like the Sensenich spacer we intend to use in terms of thickness and circumference.

Once we had the cowl where we wanted the nose to be, we drilled straight thru the wooden spinner Chet made and into the cowl. Next, we installed temp plate nuts into the cowl so that we could use long 8/32 screws and lock the cowl in the exact same place every time.

What took us almost a month on the 9A took us only 2 days on the 6A. In the next photo, I circled the location of the 8/32 screws.

cowlregistration2.jpg


Side view.....

cowlregistration.jpg
 
Thanks for the suggestions. After re-reading the instructions I think I will fabricate up the strips on the sides, bottom and over the top.

I won't do any scalloping of the strip as I don't have the cowl and I don't know the exact spacing, but at least I will have the strip in place and riveted. Hopefully save me doing an engine/mount removal.

Are most of you using separate strips for the sides, bottom and top ?

Darren
 
Strips and hinges

On the 9A we finished two years ago we used 17 screws and plate nuts across the top, hinges along the sides (vertically and horizontally) and 12 screws and nut plates (6 & 6) along the bottom of the cowl.

After 200 hours on the 9A, it's been rock solid, it still works well, using a cordless drill (set to low torque) it's been quick & easy to disassemble, so we're duplicating it on the 6A we're building Chet.
 
I would recommend...

that you not rivet the strips in place yet, Darren. I have just drilled my strips to the firewall for my SJ cowl. Going back thru the archives, as well as going thru the SJ Yahoo group, I have seen that many have recommended that the riveting wait until the camlocs have been installed. Some say that it is much easier to do it this way. I will find out myself in the near future. ;) So, as always, check out the archives and good luck!

Darren S said:
Thanks for the suggestions. After re-reading the instructions I think I will fabricate up the strips on the sides, bottom and over the top.

I won't do any scalloping of the strip as I don't have the cowl and I don't know the exact spacing, but at least I will have the strip in place and riveted. Hopefully save me doing an engine/mount removal.

Darren
Click to expand...
 
Using Gary's advice, seems like one could cut all the strips - including the scallops - and just cleco it in place for the cowl work. ... i.e. just holding off on final riveting. Is that correct, or should one not even drill holes for clecos yet?

Terry
 
I thought the reason for riveting on the strips, prior to engine mount and engine installation, was due to lack of access once these items are in place?

Also, I don't see how permanently mounting the aluminum strips on the sides and the bottom (cleco on the top strip until the top skin goes on permanently) will hinder the fitting the the SJ cowl.

Darren
 
No, It's not the fitting of the cowl...

I understand the problem of riveting the strips on now is that it is harder to rivet the camlocs in place. If you're installing the strips all the way around the cowling, why not make it easier on yourself to installing the camlocs, rather than riveting sitting on the floor? :eek: http://www.vansairforce.com/community/showthread.php?t=28048&highlight=camloc+installation

Here's a link to MilSpec's installation instructions: http://www.milspecproducts.com/RVLancInstr.pdf This is the kit that I have.

Do a search on camloc installation. This is what you'll find: http://www.vansairforce.com/community/search.php?searchid=8567321
 
Wait

Darren,

I would wait if you can.

Just don't rivet anything on the firewall yet.
I am installing mine right now with .050 and it
is pretty easy to work.

Have not rivetted any thing but the sides and
the bottom except for 2 rivets per side on the
bottom that will be bucked later.

Hope this help,

PS---You will love the SJ cowl.
Cut off 1/2 inch and it fits perfect:D

Boomer
 
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