Single magneto driven from one of the camshaft idler gears via a pair of bevel gears at 3/4 camshaft speed; hand

control by scroll pair between the drive and armature shaft.

Bosch FH6 magneto were fitted; however, before the 1924 Grand Prix, these were replaced with the newer Bosch FHa spark-gap magnetos. In a published statement after the 1924 Grand Prix Sunbeam attributed poor engine performance during the race to this magneto replacement; however, it was also suggested that sparking plugs were responsible.

Duel magnetos were fitted for the 1925 event on the scuttle with distributors projecting through the dashboard and driven from the rear end of the exhaust camshaft; only one was in use at a time.

KLG sparking plugs fitted in the centre of the cylinder head were used in all events.