The Briggs and Stratton 14-FB fan shroud was completely rotted through on the bottom. Even back in the 1980's it had a patch pop-riveted to the bottom. This repair stretched my bodywork skills (or lack thereof).
The electrolytic de-rusting process got the part down to what was left of the base metal. It was pretty ugly.
The patch was made of comparable gauge material with the worse of the rusted sheet metal cut away. The back plate was used to hold the correct diameter and curve of the fan shroud. I kept it bolted in place while the patch was tacked into place using oxy-acetylene and a brazing rod. The brazing rod wicked pleasantly into the new patch material and surprising well onto the original part.
Here's the finished part after all the brazing was completed. Brazing was certainly a much easier option than straight welding, but still it resulted in some distortion of the sheet metal. I ground off the excess material and hammered any distorted surfaces flat. The Bondo stage and glazing putty is always the hardest for me. The Bondo sets up too fast, so I have to work in small batches. When it is sanded it always sticks to the sand paper. The glazing putty is easier to work with since it dries harder, but only covers small areas at a time. Altogether its not too bad considering what I had to start with. Its by no means perfect, but I did it myself, which is what counts for me. Its only the bottom, which is obscured when the engine is installed in the tractor anyway. You can't see straight into the shroud for this reason as well, so imperfections will be difficult to see.
The current plan for the exhaust and muffler is to use the original. It went through the de-rusting electrolyte tank and actually came out without any holes in it. The EMT conduit fitting is still serviceable into the exhaust manifold elbow, so instead of risking cracking the block, I'll just keep it. I can always make a new exhaust later if I want. I have no idea what the stock Bantam exhaust was like. My father fashioned the current muffler from a spent propane torch tank. It slings neatly under the floor board and attaches to the bolt holding the transmission in place. The nice thing about this exhaust arrangement is that it keeps the heat away from the driver.
