Re: Need spark plug explanation....AC 103 vs AC 103S vs Champ UY6

Posted by Owen_Dyneto On 2014/8/9 22:11:50

I don't know the answer, but not all spark plugs for U.S.-made cars have metric threads. Pierce, Packard, and many others used plugs with 7/8-18 thread back in the late 20s, early 30s, I think some even used NPT (tapered U.S. pipe threads).

AutoLite 3076 is a 7/8-18 threaded plug which was an extremely popular plug in it's time for cars and continued in use for a very long time for truck and commercial industrial engines, check the application list of car makes that used this plug - very extensive.http://www.autolitecatalog.com/PartDetailWindow.aspx?b=A&pn=3076