By Gary Baxter and Tim Palmer, Green Country Corvair Group, March 1995 Rear View
I recently had to fix an oil leak coming from a rubber expansion plug in the hole where the oil filler used to be on the oil filter / alternator adapter. Like many early Corvair owners I have replaced the generator with a later alternator with built-in regulator. Since I have the original F.C. oil filler which comes out of the block, there was no need for the filler in the car location. Therefore, the plug.
After consulting with Gary I found out that he used a regular freeze plug to do the job. I went to Pep Boys and found a 1“ freeze plug for $0.59. There were three different styles to chose from. I chose the deepest since I figured it would give the most surface for the oil to get past. Again taking Gary's advice, I ground a very small amount off the circumference of the plug, so it wouldn't fit to tight and break the casting. Before I drove the freeze plug in, I coated the hole lightly with J-B Weld to provide a good seal.