Spark plug size adaptor assembly

A spark plug assembly comprising:

• a spark plug having an external mounting thread at one end and a pair of electrodes extending outwardly of the mounting thread, the spark plug further including a terminal at the opposite end, the spark plug also including a hexagonal flange for use in rotating the mounting thread to insert or remove the spark plug, and a top insulator positioned between the hexagonal flange and the terminal;
• a housing comprising a sleeve having a first end defining an external thread sized and configured to couple with an ignition harness of a spark-ignited aircraft engine and a second end defining a hexagonal-shaped cavity sized and configured to receive the hexagonal flange of the spark plug, the top insulator and terminal of the spark plug being received within the sleeve and the hexagonal flange of the spark plug being received within the hexagonal-shaped cavity of the housing, the housing further defining an external hexagonal flange for use in securing the housing to the spark plug port of an aircraft engine;
• a coupling secured to the housing and including an internal thread configured to receive the external mounting thread of the spark plug, the external mounting thread of the spark plug being threadingly received within the internal thread of the coupling, the coupling further including an external thread configured to be received by the aircraft engine;
• and
• an insulator received within the sleeve and surrounding the top insulator of the spark plug.