Back in the bad old days when cars ran leaded gas & transistors were
only found in spacecraft, there was an after market plug with
construction known as 'surface gap'. The porcelain filled the area
between the electrode & thread body. The 'gap' was the distance from the
electrode to the thread body.

Anyone know whether these plugs are still available? It would seem that
if nothing else, it might make cleaning the lead a bit easier.

Charlie

Mercury outboards used that plug for their CD ignition systems. I have used the Autolite AR2592 in the race engine with good result. Autozone will order them for you (one day) and the cost was $7.00 for 4 plugs. And used to run the Champion N59G in all racing rotaries. Also the Champion N86 for a bit warmer tip. We now use NGK R6725-115 retracted gap, fine wire electrodes, at $28.00 each, and they work great, but if they were not gifted to us we would use the Autolites again. We also run an MSD-6AL on leading and trailing, so fouling is never a problem.

 

Lynn E. Hanover