Abstract: A cam shaft assembly for an engine has a hollow elongate shaft with a plurality of cam lobes and bearing journals received on and positioned along the shaft in a predetermined spaced apart relationship. The cam lobes are further oriented angularly in a predetermined alignment relative to one another. A radial thrust bearing is received and positioned on one end of the shaft. Each of the elements is secured to the shaft by mechanically expanding the shaft into an interference relationship with an opening in each element. A cam timing gear is fastened to the one end of the shaft by a fastener passing through the gear and into the one end of the shaft. Threads formed on the fastener engage complimentary threads formed on the internal surface of the shaft to allow the cam gear to be torqued down. A recess is formed in the shaft, the cam gear or both for receiving a projection or key which accurately aligns the gear to the cam lobes on the shaft and locks the gear in position.