Abstract: The invention relates to a valve-controlled system, particularly for use in an internal combustion engine, comprising a valve stem and a valve disc extending at an oblique angle to the axis of the valve stem. The valve disc is adapted to be lifted from an associated valve seat and is non-circular and preferably elliptical. By means of a turning drive the valve is adpated to be rotated to open and close chambers or passages which open into the valve seat.