Valve timing drive The timing belt (toothed belt) is wrapped around the camshaft pulley and which other engine pulley?

Introduction / Context:
Correct valve timing synchronizes camshaft rotation with the crankshaft so that intake and exhaust events occur at the right piston positions. The timing belt is the common drive method in many engines.

Given Data / Assumptions:

• Four-stroke engine: camshaft rotates at half crankshaft speed.
• Toothed belt prevents slip between pulleys.
• Some layouts route the belt around an idler and tensioner and may also drive a water pump.

Concept / Approach:
The camshaft must be phase-locked to the crankshaft. Therefore, the belt necessarily connects the camshaft pulley to the crankshaft timing pulley. Ancillary pulleys (water pump, balance shafts) can be driven but are not the fundamental pair.

Step-by-Step Solution:
Identify primary requirement: cam timing tied to crank angle.Primary pulleys: camshaft and crankshaft timing pulley.Select the option naming the crankshaft timing pulley.

Verification / Alternative check:
Service manuals show timing marks on both cam and crank pulleys; alignment confirms their direct relationship.

Why Other Options Are Wrong:
Distributors on older engines are driven from the cam, not by the belt directly in most designs.

Fan and alternator are driven by accessory belts, not the timing belt.

Water pump may be belt-driven but is not the essential mating pulley.

Common Pitfalls:
Incorrect belt tension or misaligned timing marks causes poor running or engine damage in interference engines; always lock the crank and cam before removal.

Final Answer:
timing belt drive (crankshaft) pulley