A variable camshaft timing system comprising a camshaft (36) with a vane (2) secured to the camshaft for rotation with the camshaft but not for oscillation with respect to the camshaft. The vane has a circumferentially extending plurality of lobes (20, 22, 24) projecting radially outwardly therefrom and is surrounded by an annular housing (28) that has a corresponding plurality of recesses (30, 32, 34) each of which receives one of the lobes and has a circumferential extent greater than the circumferential extent of the lobe received therein to permit oscillation of the housing relative to the camshaft. Oscillation of the housing relative to the camshaft is actuated by pressurized engine oil in each of the recesses on opposed sides of the lobe therein, the oil pressure in such recess being preferably derived in part from a torque pulse in the camshaft as it rotates during its operation. An annular locking plate (50) is positioned coaxially with the camshaft and the annular housing and is moveable relative to the annular housing along a longitudinal central axis of the camshaft between a first position and a second position. The locking plate is biased by a spring (52) toward its first position and is urged away from its first position toward its second position by engine oil pressure when engine oil pressure is sufficiently high to overcome the spring biasing force.