Engines w/ Single Chain Drive An engine timing chain synchronizes the rotation of the crankshaft and the camshafts for proper valve timing. Proper timing prevents the engine’s pistons from striking the valves as well as correct intake and exhaust timing during combustion. The timing chain is a roller chain that connects with the engine’s camshaft gears and rollers. Timing chains must be replaced after a recommended amount of distance, but generally chains are far more reliable than belts. Failure to replace the timing chain when exhibiting signs of stretching or wear can result in catastrophic engine failure. euromotiv is your source for genuine and aftermarket timing chains should you need to purchase a replacement.