Adjustable cam gears contain bolts that can be loosened to adjust phasing. Which is the correct feature?

• A. Springs that lock timing
• B. Riveted joints
• C. Bolts that can be loosened to adjust phasing
• D. Plastic spacers

Answer: (C)

Understanding cam timing control is key. Adjustable cam gears are built so you can change the alignment between the cam and the crank. They achieve this by letting you loosen bolts, rotate the gear to shift the cam’s phase, and then tighten the bolts to lock the gear in the new position. This ability to move and fix the gear’s angle is what lets you fine-tune valve timing for better power delivery, response, and efficiency, especially to compensate for belt/chain wear or manufacturing tolerances.

Springs that lock timing would freeze the timing in place without allowing adjustment. Riveted joints are fixed and cannot be moved at all. Plastic spacers might change some clearances, but they don’t provide the controlled, adjustable phasing mechanism that loosening and re-tightening bolts on an adjustable cam gear does.