Cowling advice needed - Rotax + 4:1 exhaust + warp drive

[KevinC]

I am having issues with fitting the cowl.  I have assembled all three fiberglass parts.  When pushed as far aft as possible to clear the prop mount bolt heads the cowl is dangerously close (1/4") to the bend on exhaust tube #1 - if i pull it forward a bit it seems pretty dang close to the prop bolt heads.  How much clearance is needed on the prop side and exhaust side?

thanks all!

K

[b1x4nqb]

Kevin,

Mine was also close however I noticed you didn't trim for your pump area yet.  You'll want to trim around this area on your right side intake to give you room there.  Also, my pipe was too close but I sent it back and they adjusted it to fit properly.  I am still going to lay some aluminum tape on the inside of the cowl in this area.  With respect to the prop side, mine is pretty close.  I see most also have it pretty close.  One of the factory planes built by Troy had a prop extension on it.  I thought about adding one more for getting the cowling on and off easier with the camloc's but I havn't invested the money for another thing not necessary at this point.  I've got paint fumes in the shop for now bu I'll measure when things clear out and let you know.

Paul, PA

[DaveU]

Kevin,
If I put a steel ruler, like the one in your second photo, flat across the front of the cowl, there is about 1/8" of clearance between the ruler and the heads of the prop bolts.  

I think it could have gone a little closer and been ok, but that is where I put mine.  I had to build a "bump" on the cowl to give room around the exhaust on the fuel pump side of the engine.

The exhaust only has to be about 1/2" away from the cowl, the problem with mine was that when the engine shuts down, it kicks a little and that pipe was hitting the cowl and broke/burned the glass some.

The threaded prop drive lugs like the ones Scubarider used, would leave a little more room.  Then you do not have bolt heads to deal with.  Remember the discussion  that he had to freeze the lugs, and put them in a hot prop flange to get them in?

Dave

[DaveU]

Kevin,

Here is the poor mans camloc receptacle tool.  Once the dowel is fastened to the receptacle, then you put the dowl through the enlarged hole, this aligns the receptacle with the hole, and lets you drill and cleco the first hole, then you drill the second hole, remove the jig, and then rivet the real one in place.

I enlarged the camloc holes with the step drill.  It seemed to center better, and did not grab/bend/twist/injure the user.

I realize there is probably a tool for this purpose, I did not have one, and never seen one, so I made this.  It worked for me.

Dave

[Roger]

I know this is a fairly old subject, but having just installed my cowl Camloc's, I thought I'd inject my two cent's worth. The method that I found that worked best for me, was to drill a 1/8" hole where I wanted the fastner, then enlarge it to .260 (don't remember the letter size) and while holding the receptical side in place, take the screw part, stick it through the hole and insert it into the receptical, just as you will when fastening the cowl in place, then straighten the recptical, and the spring holds enough tension on that part to be able to drill your first rivet hole. After drilling your first rivit hole, insert a rivet into that hole to hold the receptical in place, (don't flatten the rivet yet) and then drill the second hole. I drilled all my holes first then countersunk the rivet holes.
This worked for me. Hope this helps someone else.
Roger

[MH434]

I assembled all three fibreglass bits.....

I only got two bits, a top and a bottom. Is there a third piece? I'm selling mine but if there is a third piece maybe I've been short changed!

Keith

[KevinC]

The three would be the boot cowl and the two cowl halves.

k

[scubarider2]

Yep, had the same problem fitting the cowls around the exhaust pipe on the front.  After using the spacer from Warp Drive the problem was pretty well solved.  I moved the cowlings as forward as possible which left me about 3/4 in from the fiberglass.  It has blackened it somewhat but it is fine.  It really is a tight fit all over the place.  I saw several planes where they cut a hole out right where the exhaust curves then re-fiberglassed on top of that.  Looked ok but I am satisfied with the distance I got.
Dennis