What will occur if hot clearance is used to set the valves when the engine is cold?

When hot clearance is used to set the valves while the engine is cold, the result is that the valve clearances are too tight for the operating temperatures the engine will reach. As the engine warms up, the metal components expand. If the initial clearances were set with the assumption that components would be at their operating temperatures, using cold measurements causes the valves to not have enough clearance.

As a result, the hot condition causes the valves to open later than intended because of the expansion of the valve components. Since the timing of the valves is critical to engine performance, this can lead to poor engine function. Additionally, the valves may close as designed or close slightly early due to the tight clearance, but the primary consequence is that they will open late. Therefore, the proper understanding of valve timing relative to thermal conditions is crucial for ensuring optimal engine performance.