What might happen if hot clearance is used to set valves in a cold engine?

When hot clearance is used to set valves in a cold engine, it can lead to the situation where the valves open late and close early. This occurs because the valves are set with a clearance that is appropriate for the expanded metal when the engine is hot. However, when the engine is cold, the components have not yet expanded to their operating dimensions, resulting in a larger gap than intended.

As a result, the timing of valve actuation changes; the valves may not fully open for the required duration and might close sooner than they should. This can negatively affect engine performance, such as reducing efficiency, power output, and potentially causing increased wear on the valve train components over time. Ensuring the correct clearance when the engine is cold is essential for optimal performance and longevity of the engine parts.