Abstract: According to the preferred embodiment illustrated herein, the invention comprises a platform of insulating material to which a spring clip is fixed, in order that the platform can be slidably secured to the upstanding side wall of an ignition distributor cap, such cap having an integral ignition coil and an exposed coil terminal. Fixed to the platform, and projecting therefrom for a contacting engagement thereof with the coil terminal, is a flexible, electrical conductor or contactor. A spark plug, also mounted replaceably onto the platform, has the central, metallic terminal thereof in contacting engagement with the flexible contactor through a limb to which the contactor is replaceably secured. The limb is metallic, and electrical continuity is made therethrough from the central spark plug terminal to the flexible contactor. The latter projects from the platform in a normal attitude relative thereto with a reach into the center of the distributor cap whereat the coil terminal is sited.