Actually, though it is surely a "cheat" way to do it and not proper, the plug will stay in. It works because the 1/4 x 28 and the 1/4 x 32 threads are so close. Just use it in an emergency and get a proper adapter or make one as soon as you can and you'll be fine.

BTW, don't use the glow plug you modify into a tap. It is only used to "tap" the threads...

AV8TOR