Exhaust Shroud Heater Inlet Tube

Time: 2 hrs

I finally cut the hole in the cowling for the heater inlet to the exhaust shroud. It’s a bit tricky because you can’t see it and you need to mark the hole somewhat accurately. Of course after some frustration of trying to mark the hole and getting something reasonably accurate so I could drill a starter hole I figured out that if I would have removed the radiator I would have been able to see in a bit better through the front of the cowling. Still a somewhat impossible task, but it would have definitely made it a bit easier. To get some idea of where the inlet pipe would intersect the cowling I cut down a toilet paper tube to fit in between the exhaust shroud and cowling. This worked well to be able to mark one edge with a marker so I could drill a 1 1/4″ hole as a starter hole. After the starter hole was done I put the lower cowling back on and used the Dremel with a sanding drum to open up the hole so the tube would fit. After achieving a pretty nice fit I remove the lower cowling so I could more easily clean up the hole and cut back the heat shield. I also cut and riveted the inlet tube onto the exhaust shroud. Unfortunately once the tube was riveted is seems that the angle had changed a bit and the near perfect hole I had made was now a bit off. I was able to bend the inlet tube a little the get a better fit, now at least I can live with the way it is… not perfect but pretty good.

Using a cut down toilet paper tube I was able to mark one side of where the hole needed to be cut. I used a 1 1/4 hole saw to cut the initial hole an then used the Dremel with a sanding drum to open it up.

The final hole. The pipe used to be centered in the hole, but after riveting it changed the position a bit. Not a bit concern for me. I don’t want to widen the hole to make it equal all around so I’ll live with this.