Variable lost motion valve actuator and method

A lost motion engine valve actuation system and method of actuating an engine valve are disclosed. The system may comprise a valve train element, pivoting bridge, an adjustable tappet, and a valve stem. The pivoting bridge may include a first end for contacting the adjustable tappet, a second end for contacting the valve stem and a pivot point between the first and second ends for contacting the valve train element. The amount of lost motion provided by the system may be selected by varying the position of the adjustable tappet relative to the pivoting bridge. Variation of the adjustable tappet position may be carried out by placing the adjustable tappet in hydraulic communication with a control trigger valve. Actuation of the trigger valve releases hydraulic fluid allowing for adjustment of the adjustable tappet position.