Fine wire plugs have one or two wire ground electrodes while massive electrode designs have a larger center electrode.

-by Coy Jacob

While the world of piston-engine R&D focuses on electronic ignition and diesel engines, one aspect of internal combustion for airplanes hasn’t changed much: the lowly spark plug. As electronic ignition gains more service history, that may change. But for now, owners have to solve their plug problems with essentially two choices: massive electrode or fine wire plug designs.

Given how badly an engine can run without clean spark plugs of the right type, you’d think performance and economy gains are there for taking with improved spark plug technology. And while that has happened in the automotive world, as usual, light aircraft GA engines putt along in a technological backwater,…