Ignition timing refers to the moment when the engine's compression stroke ends, the piston reaches the top of its stroke, and the ignition system provides a high-voltage spark to the spark plug to ignite the compressed air-fuel mixture in the cylinder for power generation. This moment is the ignition timing. Below are the steps to adjust the ignition timing: 1. Adjust the breaker contact gap of the distributor. 2. Locate the top dead center position of the first cylinder's compression stroke and loosen the first cylinder's spark plug. 3. Install the dial indicator bracket and head, ensuring the indicator's contact point vertically touches the exhaust valve spring seat with appropriate pressure, ideally keeping the small pointer on the dial indicator between 1-2. 4. Rotate the dial to set the large pointer of the dial indicator to '0'. Attach an angle disk to the flywheel and slowly rotate the flywheel, observing the dial indicator's pointer. When it moves away from '0', this marks the exhaust valve opening time, and the angle disk pointer should be adjusted to '0'. 5. Continue rotating the flywheel until the bottom dead center mark aligns with the radiator's reference line. The angle indicated by the angle gauge at this point is the exhaust valve opening angle before the bottom dead center. 6. Keep rotating the flywheel until the dial indicator pointer returns to '0', marking the exhaust valve closing time. The angle indicated by the angle gauge now represents the exhaust valve opening duration angle. 7. Use the same method to check the intake valve's opening and closing times and its opening duration angle, then adjust the distributor to the optimal ignition timing.
