An ignition coil assembly of the type which is directly mounted onto an associated internal combustion engine spark plug. The coil assembly includes a spark plug boot section made of a highly elastic material with an inside cylindrical passageway. The inside passageway features ribs which engage a high voltage connection coil spring positioned in the passageway to make an electrical connection between the coil and spark plug high voltage terminals. The spring has a generally constant outside diameter outer section except its end segments have a reduced diameter where they contact the high voltage terminals. The passageway ribs retain the spring in position prior to its installation and after its removal from the associated spark plug.