Abstract: A spark plug for an internal combustion engine; the plug including a pair of electrodes spaced alongside each other, and extending through an insulator fitted in a metal casing that is threaded, so as to be screwed into the engine, each electrode being intercepted by a solid state H.V. time delay device, which, in one example thereof, may comprise a high voltage diode, and, in another example, may comprise a solid state semi-conductor or the like.