When adjusting valve lash on a four-cylinder engine, if the valve clearance is set too tight, which of the following could occur?

Setting the valve clearance too tight can lead to the valves not closing properly. In an internal combustion engine, proper valve operation is crucial for maintaining the correct air-fuel mixture and exhaust flow. When the clearance is insufficient, there is not enough space for the valve to fully close due to thermal expansion or other factors. This improper closure can lead to several problems, including a loss of compression in the cylinder, which can significantly affect engine performance.

When valves do not close completely, it can cause issues like poor combustion, reduced power output, and increased emissions. Additionally, if the valves are kept open too long or do not seal properly, it can lead to backfiring and misfires, along with potential damage to the valve seats and the valves themselves over time. Focusing on valve clearance is essential for smooth engine operation, thus making it critical to ensure that the specifications are followed correctly during adjustments.