What is Ignition Timing?
Ignition Timing is a process to deliver spark at the correct time. It sets the pointer with respect to the piston's position and the crankshaft’s velocity. Thus, it delivers the spark at the most accurate timing to burn the air-fuel mixture. The Ignition System provides a spark at the end of the compression stroke in the combustion chamber at an appropriate time. Hence, it is known as Ignition Timing. You should set the timing according to the engine design and as specified by the manufacturers. If the spark occurs too early or too late in the engine cycle, it results in excessive vibrations. It may also cause damage to the engine.
Ignition timing also affects several variables. They include the engine power, torque, fuel economy, and also the engine’s life to some extent. Modern engines’ control unit uses a computer to control the ignition timing more precisely. The earlier generation cars required the driver to control or adjust the timing as per the driving conditions. However, these days, in modern car engines, those actions have been automated. Whenever you carry out any major changes to the engine, you may also need to implement the necessary changes in the ignition timing.
The manufacturers provide the 'Timing Marks' as the indicators for setting up the ignition timing for the engine’s ignition system. The manufacturers carve out/punch these marks on the crankshaft number of degrees before the Top Dead Centre (TDC). The engine-makers normally punch the timing marks on the vibration damper at the front or on the flywheel at the rear of the engine.
At times, these marks are located on the crankshaft pulley or the largest radius that rotates at the speed of the crankshaft. Timing marks indicate in terms of the number of degrees before the Top Dead Centre (TDC). The older engines used the timing light for setting up the ignition timing.
You can set the ignition timing at the correct point of firing while the engine rotates. However, it has to be exactly a few degrees before the Top Dead Centre (TDC), which could advance with increasing engine speed. You can adjust the timing by loosening and/or rotating the distributor on its seat. Modern engines come with a crank angle sensor that directly connects to the engine management system. The crankshaft's timing marks must also match with that of the camshaft for achieving the correct valve timing.
Automatic Ignition Timing Advance:
There is a certain delay called the 'Ignition delay' to start the combustion after the spark is fired. The spark must occur before the moment at which the cylinder reaches the maximum pressure. Ignition Advance is the difference between this moment and the occurrence of the spark.