Ajoitusmerkinnät

Ajoitusmerkinnät, often translated as timing marks or ignition timing marks, are crucial indicators used in internal combustion engines to ensure the correct synchronization between the engine's rotating components and the ignition system. These marks help mechanics and technicians set the precise moment when the spark plug fires in relation to the piston's position.

The primary timing marks are typically found on the crankshaft pulley or flywheel and on the camshaft pulley or sprockett. They are designed to align with corresponding marks on the engine block or timing cover. The crankshaft pulley marks usually indicate Top Dead Center (TDC) for cylinder number one, or specific degrees before TDC, which is the optimal point for ignition. Camshaft timing marks, on the other hand, ensure the camshaft is correctly positioned relative to the crankshaft, controlling valve opening and closing events.

When setting ignition timing, a timing light is used. This device flashes in sync with the spark plug firing. By observing the flashing light and the timing marks, one can determine if the ignition is occurring at the correct point in the engine cycle. If the marks are not aligned, the ignition timing needs adjustment, usually by rotating the distributor (in older engines) or by recalibrating the engine's computer (in modern engines).

Incorrect timing marks can lead to a variety of engine problems, including poor performance, reduced fuel efficiency, increased emissions, and potential engine damage. Therefore, maintaining accurate timing marks is essential for the efficient and reliable operation of an internal combustion engine.