[Royce P]

We used to have a Champion spark plug cleaner / tester. It used a fine glass bead. Unfortunately after cleaning the porcelains of the plugs were etched which caused them to foul almost immediately.

Fortunately Model T spark plugs - the original kind - are two piece so that you can easily take them apart and clean them with a solvent (I use carburetor cleaner like Berrymans's B12) and a brass brush.

This seldom needs to be done. In general the only way a plug gets fouled is if there is some other problem like bad rings or misadjusted fuel mixture. Or using a "modern" plug with the little adapter thingies. I watched a guy on one of our club tours go through ten plugs in less than 20 miles. He then went to an auto part store and bought another 10 plugs so he could get home. Then I saw him do the same thing on our next club tour.