Series gap spark plug

Claim 1

A series gap spark plug comprising a metal body member adapted to be positioned on an engine with its firing end projecting into the cylinder and forming the ground electrode, an insulator member having a rib formed on the top thereof and positioned within said metal body in gas-tight relationship therewith and having a centerbore axially therethrough, a center electrode positioned within said centerbore with the firing end thereof adjacent said ground electrode, the other end of said center electrode being positioned within said centerbore intermediate its ends and in gas-tight relationship with said insulator, a terminal screw positioned in loose fitting relationship within the upper portion of said centerbore to form a space therebetween, the inner end of said terminal screw being spaced apart from the upper end of said center electrode to form an auxiliary spark gap, a cap-like member provided on the upper end of said terminal screw with its disk portion positioned on the upper end surface of said insulator, the annular wall portion of said cap-like member extending over said rib and being secured thereto to retain said terminal screw within said centerbore, and means providing a gas venting path along the inner surface of said cap-like member between said space and the atmosphere to serve as a pressure relief from and temperature control for said auxiliary spark gap.