ENGINE VALVE ASSEMBLY INCLUDING A STOP MECHANISM FOR INCREASING A FORCE TO BIAKE A VALVE TO A CLOSED POSITION

The invention relates to an engine valve assembly including a stop mechanism that increases a force biasing a valve toward a closed position when the valve is in or near the closed position. A valve assembly includes a valve body defining an inner bore therein, a valve stem, a spring holder, a valve spring, and a stop mechanism. A valve stem extends through an inner bore in the valve body and is adjustable between an open position and a closed position. The spring holder is spaced from and fixed relative to the valve body along a longitudinal axis of the valve stem. The spring holder defines an inner bore through which the valve stem extends. A valve spring is captured between the valve body and the spring holder and is configured to apply a biasing force to the valve stem that biases the valve stem toward the closed position. The stop mechanism is configured to increase a biasing force applied to the valve stem when the valve stem is in the closed position or within a predetermined distance from the closed p