Which component is used to adjust cam timing by rotating to align marks and selecting different timing positions?

• A. Offset Cam Bushings
• B. Adjustable Cam Gear
• C. Multi-keyway Crankshaft Gear
• D. Checking Pushrod

Answer: (B)

Cam timing is about controlling when the valves open and close in relation to the piston position. To adjust it, you need a way to rotate the cam relative to the crank until the timing marks line up correctly for the desired advance or retard position. An adjustable cam gear is designed for this purpose: it sits on the camshaft and offers multiple alignment positions (often via extra keyways or slots). You rotate the gear to the chosen position so the marks align with the engine’s timing references, then lock it in place. This directly changes the cam’s rotation relative to the crank, giving precise control over valve timing.

The other options aren’t used for selecting timing positions in this way. An offset cam bushing shifts the cam position within its bore but doesn’t provide selectable timing marks in the same way. A multi-keyway crankshaft gear alters timing from the crank side rather than adjusting the cam gear itself. A checking pushrod is a measurement tool, not a timing adjustment device.