How does excessive valve clearance affect engine performance?

Excessive valve clearance can significantly impact engine performance, primarily by disrupting the timing and effectiveness of the engine's airflow and combustion processes. When there is too much clearance, the valves may not seat properly against the valve seats, leading to incomplete sealing. This can cause a reduction in the compression ratio, as the engine is unable to compress the air-fuel mixture adequately.

Moreover, excessive clearance can delay valve timing, which can lead to inefficient intake and exhaust cycles. This misalignment affects the engine's ability to draw in the correct amount of air-fuel mixture and to expel exhaust gases effectively, ultimately resulting in a loss of power and overall engine performance. Therefore, maintaining the correct valve clearance is critical for optimal engine operation and performance.