Abstract: An improved locking type spark plug gasket in which the locking lugs are of such configuration as to lie within the vertical height of the sealing folds of the gasket. The configuration especially adapts it to receive a synthetic resinous coating applied after manufacture, and facilitates installation on that type of spark plug having an undercut area at the base of the threaded shank portion thereof.

Abstract: An improved tool for installing captive type spark plug gaskets upon a spark plug body characterized in the provision of a staking member which contacts the inwardly directed locking flange of a gasket in such manner as to form undulations in the plane thereof to provide the equivalent of metal thickness which is appreciably thicker than the original thickness of metal stock from which the gasket is formed. During a staking operation, the inwardly directed flange is further inwardly folded to reduce the effective diameter of the free edge portion thereof, so as to be positioned to lie upon the unthreaded undercut area adjacent the lower transverse surface of the plug body. Because of the effective increased thickness of the free edge of the inwardly folded flange, cross threading with respect to the thread of the shank does not occur when the plug is unthreaded from an engaged cylinder head opening, and the gasket remains captive on removal.

Abstract: An improved spark plug gasket particularly adapted to be installed in locked relation upon a spark plug body of a type having a fully threaded shank. The gasket includes the usual sealing flanges and a plurality of inwardly extending locking members or tabs which are staked directly against the threads of the shank adjacent the base portion thereof. A wedge-like staking tool engages the locking members as it is inserted in an interstice between the sealing flanges and the locking members to radially inwardly force the locking members against the threads on the shank, and deform the locking members to at least partially conform to the threads.

Abstract: A captive spark plug gasket in which the means for maintaining the captive relation is in the form of an inwardly directed flange, the free edge of which is folded upon itself to provide the equivalent of metal which is appreciably thicker than the original thickness of the metal stock from which the gasket is formed. During a staking operation, the inwardly directed flange is further inwardly folded to reduce the effective diameter of the free edge portion thereof, so as to be positioned to lie upon the unthreaded undercut area adjacent the lower transverse surface of the plug body. Because of the increased thickness of the free edge of the inwardly folded flange, cross threading with respect to the thread on the shank does not occur when the plug is unthreaded from an engaged cylinder head opening, and the gasket remains captive on removal.

Abstract: A captive spark plug gasket in which the means for maintaining the captive relation is in the form of an inwardly directed flange, the free edge of which is provided with a plurality of staked undulations to provide the equivalent of metal which is appreciably thicker than the original thickness of the metal stock from which the gasket is formed. During a staking operation, the inwardly directed flange is inwardly folded to reduce the effective diameter of the free edge thereof, so as to be positioned to lie upon the unthreaded undercut area adjacent the lower transverse surface of the plug body. Because of the increased thickness of the free edge of the inwardly folded flange, cross threading with respect to the thread on the shank does not occur when the plug is unthreaded from an engaged cylinder head opening, and the gasket remains captive on removal.