A central bolt for attaching a camshaft phaser to a camshaft of an internal combustion engine. The bolt also functions as oil supply means and is provided with a first longitudinal passage, for supplying engine oil under pressure from a front camshaft bearing to an oil control valve disposed in an outer cover of the phaser, and with second and third longitudinal passages for supplying phaser control oil from the oil control valve to advance and retard chambers within the phaser.