PURPOSE: To adjust the timing of a compression release engine brake with electrically controlled mechanisms.

CONSTITUTION: In a compression release engine brake, electrically controlled mechanisms 50 are provided to selectively control the positions or motions of the engine brake slave pistons which periodically open the exhaust valves 140 in the associated internal combustion engine 100 when engine braking is desired. The electrically controlled mechanisms 50 for such purposes as controlling the 'lash' of the engine brake or controlling the timing and duration of exhaust valve openings. Because these mechanisms 50 are electrically controlled, they can be made to operate substantially instantaneously.