Surface gap spark plugs ?

[roverman]

As advertized in JC Witney,"not an endorsement". Anyone used these ? Results ? David Vizard says conventional plug, at or near center of combustion chamber, is worst for emissions, and power because of "crevice volume", side of piston, down to first ring. roverman.

[BlownMGB-V8]

Apparently they were common in Mercury two stroke outboard motors. Possibly for anti-fouling reasons.

Jim