Gear-Driven Camshaft, Helical Timing Gears & Cover

Unlike virtually every V6 and V8 truck engine that relies on a timing chain or rubber belt, the Ford 4.9L inline-six drives its camshaft directly through a pair of meshing helical gears housed behind the die-cast front timing cover.

This assembly combines the 12-lobe chilled cast-iron camshaft, four pressed-in babbitt cam bearings, the steel crankshaft drive gear, the larger composite/phenolic camshaft driven gear, the bronze thrust plate that controls cam endplay, the front timing cover, and the stamped side pushrod inspection cover.

2:1 Counter-Rotating Helical Mesh: Because a four-stroke engine fires each cylinder once every two crankshaft revolutions, the camshaft gear has exactly twice as many teeth as the crankshaft gear. Direct gear mesh means the camshaft rotates in the opposite direction of the crankshaft at an exact 0.500:1 ratio.

Controlling Helical Thrust: Helical gear teeth engage gradually for quiet operation, but their angled cut generates axial thrust along the camshaft. A hardened spacer ring and two-bolt thrust plate trapped behind the cam gear hub lock axial endplay to a few thousandths of an inch.