Patent ID: 7533640

Claim:
A piston combustion engine comprising: gas intake valves and gas exhaust valves; said gas intake valves and gas exhaust valves positioned over at least a cam shaft; a cam on said at least one cam shaft has a base circular outline and the base circular outline has a radially extending cam portion; for at least one of a plurality of valves, preferably gas exhaust valves engaging the cam, a contour body with at least an additional radially extending cam portion is provided and the contoured body is positioned in the base circular outline of the cam from a superior active position, wherein the additional contoured body is in the form of a mushroom, comprising: a part of one of the plurality of valves; an elongated hub cam and a guide body, which are preferably cylindrical, wherein the elongated hub cam extends on at least one side in a groove transverse to the cam shaft axle in the base circle outline and/or cam profile of the cam shaft in the form of an anti-twist plate with the guide body lying radially inside a guide, preferably in a guide bore, extends in the cam shaft and the additional contoured body is radially adjustable.