Toyota Genuine Crankshaft Timing Pulley

A crankshaft timing pulley is a part of an internal combustion engine that synchronizes the rotation of the crankshaft and the camshaft(s) so that the engine's valves open and close at the proper times during each cylinder's intake and exhaust strokes. The pulley train with a two to one reduction through which the crankshaft drives the camshaft and thus controls valve timing in a four stroke cycle internal-combustion engine. It is marked with tiny increments all around its perimeter, which correspond to degrees of timing from the straight-up timing position of the camshaft and crankshaft.