What part controls the flow of fuel/air mixture intake and exhaust through an up and down motion?

The camshaft plays a critical role in controlling the flow of the fuel/air mixture into the engine and the exhaust gases out of it through an up and down motion. This component is linked to the engine’s timing and is responsible for opening and closing the engine's valves at the correct intervals during the four-stroke cycle—intake, compression, power, and exhaust.

As the camshaft rotates, its lobes push against the rocker arms, which then open the valves, allowing the air-fuel mixture to enter the cylinder and enabling exhaust gases to escape after combustion. This precise timing is essential for the engine to operate efficiently and is crucial for engine performance.

While the crankshaft and pistons also contribute to the engine's overall operation, they perform different functions. The crankshaft converts the linear motion of the pistons into rotational motion, while the pistons move up and down within the cylinders, creating the necessary compression and power strokes. The flywheel, on the other hand, stores rotational energy and helps smooth out the engine’s power delivery but is not involved in the basic intake and exhaust valve operation.