If the actual measured clearance of a valve is more than specified, what should be done?

When the actual measured clearance of a valve is more than specified, the appropriate action is to select a thinner shim. Valve clearance refers to the distance between the valve stem and the rocker arm or adjusting screw when the engine is at rest. Proper clearance is crucial for ensuring optimal engine performance, as excessive clearance can lead to noise, poor engine operation, and accelerated wear.

Using a thinner shim reduces the distance between the valve stem and the rocker arm, effectively decreasing the clearance to within the manufacturer's specified range. This adjustment helps maintain the correct timing of the valve events and ensures that the engine runs smoothly and efficiently.

Opting to leave it as is would not address the excessive clearance issue, potentially leading to operational problems. Choosing a thicker shim would further increase the clearance, exacerbating the problem. While replacing the entire valve is an option in some scenarios, it is often unnecessary and more costly than simply adjusting the shim thickness to achieve the correct clearance.