Abstract

A camshaft assembly for an internal combustion engine has a hollow outer shaft with slots along its length and an inner shaft with holes along its length. The holes on the inner shaft are aligned with the slots on the outer shaft. A first set of cam lobes are fixed to the outer shaft and a second set of cam lobes are placed on the slots of outer shaft with a clearance fit. A means fixes the second set of cam lobes to the inner shaft, while simultaneously allowing the second set of cam lobes to be a clearance fit to the outer shaft. The means fixing the second set of cam lobes to the inner shaft may be a hollow pin which is hydroformed or a rivet insert which is expanded by insertion, pulling, and removal of a threaded rod.