A valve actuating apparatus for an internal combustion engine having selectively energizable intake/exhaust valves. Oil is supplied to valve actuators which perform the selective energization of the valve through a spool valve. The spool valve has a bypass for supplying operating oil to the actuators when the spool valve is set to the unenergized position in an amount insufficient for energizing the actuators but sufficient to purge air from the lines connecting the spool valve to the actuators. By so doing, the responsiveness of the actuator system is improved.