Long long ago I used one of those rubber expandable drain plugs to seal the drain hole on my Pontiac 455. It was totally stripped and at the time I needed to seal it up fast. Remember those rubber expandable plugs you could get almost anywhere? You pushed it in with a green plastic push rod and removed it the same way. I had forgotten all about it and of course I have no idea where the push tool is. Instead I ground a smooth ball end onto a long aluminum gutter nail and used that to unseat the plug. Amazingly it came out with out puncturing or crumbling. At least 30 years old and made in USA and still good! But a standard 1/2"-20 drain plug bolt was not even grabbing at all so I had to use an oversize plug. They sell oversize bolts but what size to use? Single, double, triple oversize? I saw that the two most common standard size plugs were 1/2" and 14mm. I then remembered that 14mm is the size of spark plugs and I had a tap kit for stripped spark plug holes. Since the pilot drill for 14mm is 12.8mm and a 1/2" drill is 12.7mm I used a 1/2" drill bit to open the stripped hole enough for a tap. Then I tapped the hole to 14mm and the new standard 14mm drain plug bolt fit perfectly. Now instead of needing a special bolt I can use any 14mm drain bolt. Pretty easy fix for a common problem.
