What is the engine valve clearance?

[StEloise]

For diesel engines, the intake valve clearance is 0.25-0.30 mm, and the exhaust valve clearance is 0.30-0.35 mm. Most valve clearance parameters range between 0.15-0.4 mm, with the optimal adjustment being between 0.2-0.35 mm. More details are as follows: 1. Valve clearance is set to ensure the proper functioning of the internal combustion engine's valve train. Since the valve train operates at high speeds and elevated temperatures, components such as valve lifters and valve stems expand when heated. This can automatically open the valve, preventing it from sealing tightly against the valve seat and causing leakage. 2. To prevent this phenomenon, during the design of the valve train, a certain gap is maintained between the end of the intake and exhaust valve stems and the adjusting screw on the lifter (or rocker arm). This gap is known as the valve clearance.