Fitting front exhaust elbow

Back to the custom muffler. The front elbow still has to be fit onto the muffler. I can’t build this as a single piece, as the elbows are attached to the cylinder heads with thread in different directions. My idea is to keep the front elbow as a separate piece and connect it to the muffler using teflon tubing. The front elbow was already bent in the right direction, now I also cut it to the right length, could be a little shorter still, but this at least gives me room enough to work on the connection:

I had to come up with a way to mark the exact shape of the hole to cut for the angled connection to make between the two pipes. Again, angled in all directions, so it will not be a circular hole. And it has to be in the exact right location, as there’s no room for play. Also, the muffler was quite a lot of work up until this point, so I didn’t want to make a mistake here. Only one chance to get it right. After a bit of thinkering I came up with a solution using toothpicks. I put tape with the sticky side outwards on the exhaust pipe and stuck toothpicks to it so they just touched the muffler:

Secured it with another tape on the outside when finished, took it off and got my template:

Transfered to paper, then to a piece of pipe, and cut it in the exact right angle. This is a temporary piece solely used to mark the hole to cut:

I used a piece of wood to connect the two pieces, so I could extend it to the right length and get it in a straight line with the exhaust pipe:

Then I used pieces of tape to tape off the contour of the exhaust pipe:

Removed the temporary piece and got the exact shape and location of the intersection of the two shapes in 3D:

Traced it with a marker, ready to start cutting:

Cut the marked hole and gradually grinded it bigger, adjusting the shape bit by bit, until it exactly fit the new pipe in the right angle. Went rather quick due to the experience I gained with the first hole on the other side:

And stuck things together, not soldered yet, no glue or tape, it just fits and holds like this. Quite happy again with the fit:

I expect this connection to be easier to solder. Last time we had to connect 1 mm copper to 0.32 stainless steel. This extra piece of pipe I will use now is a 0.5 mm stainless steel one, which matches the material of the muffler way better, so it will be easier to heat them evenly. The pipe used will be a little bit shorter in the end by the way, as I want some play between the two pipes underneath the teflon connection. Too bad it won’t stay all metal, because I think that’s prettier, but it is what it is, I need to make it out of two separate parts.