The camshaft is located in the upper left side of the block. The camshaft is driven by gears at the front of the engine. Seven bearings support the camshaft. A thrust plate is mounted between the camshaft drive gear and a shoulder of the camshaft to control the end play of the camshaft.
The camshaft is driven by an idler gear which is driven by the crankshaft gear, so the camshaft rotates in the same direction as the crankshaft (CCW as viewed from the flywheel). There are timing marks on the crankshaft gear, idler gear, and the camshaft gear to assure the correct camshaft timing to the crankshaft for proper valve operation.
As the camshaft turns, each lobe moves a lifter assembly. There are two lifter assemblies for each cylinder. Each lifter assembly moves a push rod and valve (either intake or exhaust). The camshaft must be in time with the crankshaft. The relation of the cam lobes to the crankshaft position cause the valves in each cylinder to operate at the correct time.