Which component, when installed, allows the cam timing to be adjusted by rotating and aligning with a timing mark?

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

Answer: (D)

Setting cam timing hinges on aligning timing marks between the cam gear and the crank so the valves open at the correct moments in relation to the piston position. An adjustable cam gear is designed for this exact purpose: it lets you rotate or offset the cam gear on the camshaft so the timing marks can be aligned precisely with the engine’s reference marks. Once the marks line up at the specified position (often around top dead center), you lock the gear in place and the timing is set, allowing the valves to open at the intended crankshaft angle.

Other components don’t provide this straightforward, built-in adjustability for cam timing. A multi-keyway crankshaft gear affects crank timing relative to the crankshaft rather than the cam; it doesn’t let you fine-tune the cam’s position with timing marks. Offset cam bushings can move the cam slightly in its journals but aren’t typically used to align timing marks during assembly. Checking pushrod is a method for verifying valve clearance, not for setting or adjusting cam timing.