What is the likely result of grinding the valves of a reciprocating engine to a feather edge?

Grinding the valves of a reciprocating engine to a feather edge can result in preignition and burned valves. This occurs because a feather edge increases the likelihood of poor sealing between the valve and the seat, which can lead to the valve not closing completely or sealing improperly under high temperatures and pressures. In this condition, the heat from the combustion process can be conducted poorly or lost, leading to hotspots that may ignite the fuel-air mixture prematurely, known as preignition.

Additionally, the feathered edge decreases the surface area for proper sealing, which can allow exhaust gases to escape and create excessive heat that further increases the risk of burning the valves. Ultimately, the integrity of the combustion process is compromised, resulting in engine inefficiency and potential damage over time.

Maintaining proper valve geometry is crucial for optimal engine performance, as it ensures that valves seal correctly and operate within their intended thermal and mechanical limits.