The present invention is a novel non-splined shaft for connecting cam units (cam sections) in a series to construct a camshaft having zero degree backlash for use within an engine. Such engines typically use a camshaft comprised of a plurality of separate camshaft units (cam sections) which are connected in a series by one or more cam connecting shafts. The entire series of camshaft units and cam connecting shafts may be, for example, 40 feet in length. Examples of natural gas engines in which the cam connecting shafts described herein may be used include, but are not limited to, the INGERSOLL-RAND KVR and KVT series of engines.