Well fellows, I think that after it's all said and done and taken to the bank, you can praise (quite legitimately) all the advances brought about by Nelson/Galbraith and turbo plugs etc., but none of those options exist as a pratical matter for Spitzy's, K&Bs, Atwoods, Wen-Macs, McCoys, Gilberts, Foxes, Cubs, etc. The only practical solutions (other than for those who have personal machine shops) will be to keep trying to find a contemporary 1/4" conventional plug that delivers OEM performance for these engines and in the cases of the aforementioned brands with glow heads, bore and tap them out for these same elusive 1/4" plugs.