Abstract

A variable camshaft timing system for an internal combustion engine comprising a housing having an outer circumference for accepting drive force, a rotor for connection to a camshaft coaxially located within the housing capable of rotation to shift the relative angular position of the housing and the rotor, a locking pin, and a centrifugal valve. The locking pin is slidably located and radially moveable in a radial bore from a locked position in which the inner end fits into the recess defined by the housing, locking the relative angular position of the rotor and housing, to an unlocked position in which the inner end does not engage the receiving hole defined by the housing. The centrifugal valve is in fluid communication with an inlet line coupled directly to an engine oil supply controlling flow of oil to the locking pin.