When I dropped the engine back in the automatic tensioner for the accessory belt hit the 2” x 6” chassis tube. This happened because I increased the supercharger belt from 8 to 10 ribs and I moved the A/C compressor and alternator to a 6-rib belt running off of a pulley mounted to the front of the super damper. I had two options: (1) modify my elegant design (if I say so myself LOL) which would likely require me to swap the automatic tensioner for a manual one (ugh) or (2) I could scallop the chassis. I decided to do the latter.
I needed to cut a semicircular hole and the easiest way to do that was with a hole saw. However, the geometry of the cut located the pilot bit 80% into the edge of the 1/4” thick tube and 20% hanging out in free space, probably the worst possible location. The solution was to fabricate a drilling jig from scrap 1/4” steel. Two screws mount it to holes tapped into the 2” x 6” and the bottom hole retains the pilot bit. The jig stays in place because the hole saw was only plunged 5/8” and the bottom edge is stiff enough to keep it in place. Once the semicircle was cut a cutoff wheel was used to cut the underside of the tube.
An insert was fabricated from two pieces of 1/8” 6061 and welded into place. Plenty of clearance was provided to mitigate heat soak and to prevent binding during engine installation and removal.
OK, I think that now, short of some other unforeseen issue, work can begin on the exhaust!