ACDelco GM Original Equipment Engine Timing Chain Kits synchronize the rotation of the crankshaft and camshaft(s) in an internal combustion engine. They help ensure that the engines valves open and close at the proper time during each cylinders intake and exhaust strokes, and are GM-recommended replacements for your vehicles original components. These original equipment timing chain kits contain components that will provide the same performance, durability, and service life you expect from General Motors.