Denny, there was an article in the Old Cars Weekly not to long ago about the AC plugs. IF my memory is correct I think the AC stood for Allis Chalmers....or some other guy named Chalmers. It also listed when GM purchased it but If forgot.
I wiah I hadn't gave that article away!!
EDIT: OOOOOK, a nice fellowbolter just "clued me in"... I am incorrect.
It was Albert Champion and NOT Allis Chalmers.
EDIT AGAIN: Here's the story as told to me.
In 1878 Albert Champion was born in France. He was an avid race fan, and began competing in bicycle and motorcycle races. Shortly after the advent of the automobile, he gained an interest in auto mechanics and automobile racing. At that time, most spark plugs were imported from France, and were very expensive. Seeing a need for more spark plug manufacturers, Champion, along with W.C. Durant (who later became president of General Motors) opened the "Champion Ignition Company" (later to become Champion Spark Plug Company), a shop that manufactured spark plugs and magnetos for the fledgling auto industry. In 1905 a falling out between himself and his investors left Champion without a company, or a name, as the investors were allowed to keep the Champion name. A new company was formed and incorporated in October of 1908 with the backing of the Buick Motor Co., and renamed it the "AC Spark Plug Company", hence his initials are what the "AC" means. (AC = Albert Champion). On October 27, 1927 Albert Champion died, and General Motors acquired 100% interest in the AC Spark Plug Company through the purchase of the remaining stock held by his estate.
I'd give the proper person credit but he may want to remain unknown.
Thanks...now we have the rest of the story.