Abstract: A spark plug assembly is provided with an insulator body extending along a longitudinal axis and defining a first face extending radially and positioned between the first and second ends. A central electrode extends through the insulator body, and a side electrode is connected to the insulator body for rotation therewith. A retainer is connected to the second end of the insulator body and defines a second face extending radially. A jacket is rotatably supported by and surrounds the insulator body. The jacket is positioned between the first and second faces, and defines an inner surface and a threaded outer surface. A bushing is rotatably supported by and surrounds the insulator body, is positioned radially between the jacket and the insulator body, and is positioned between the first and second faces. The bushing defines a tapered outer surface to mate with the inner surface of the jacket.