Abstract: A method of manufacturing a cam for a camshaft, comprising the steps of continuously applying, to a billet having a volume larger by a specified volume than a final product, a plurality of cold forging steps formed of a preliminary outline upsetting, an outline drawing, a simultaneous piercing of inner and outer diameter surfaces, a press-molding forming excess amount as burrs on the inner diameter surface, a piercing of the inner diameter surface for removing the burrs from the inner diameter surface, and a simultaneous ironing of the inner and outer diameter surfaces. The final finishing (machining) of a cam (profile) surface can be eliminated, and the final product of the cam for the camshaft having a high dimensional accuracy can be provided.

Abstract: A method of manufacturing a cam for a camshaft, comprising the steps of continuously applying, to a billet having a volume larger by a specified volume than a final product, a plurality of cold forging steps formed of a preliminary outline upsetting, an outline drawing, a simultaneous piercing of inner and outer diameter surfaces, a press-molding forming excess amount as burrs on the inner diameter surface, a piercing of the inner diameter surface for removing the burrs from the inner diameter surface, and a simultaneous ironing of the inner and outer diameter surfaces. The final finishing (machining) of a cam (profile) surface can be eliminated, and the final product of the cam for the camshaft having a high dimensional accuracy can be provided.

Abstract: A fuel supply passage leading to a fuel tank is connected to an intake side of a fuel pump of a diaphragm-type carburetor, and a fuel transfer chamber incorporated in an intermediate portion of the fuel supply passage is provided in an insulator interposed between the carburetor and an engine. The fuel pumped from the fuel tank is heated in the chamber moderately, thereby decreasing the difference in temperature between the carburetor and the fuel introduced into the carburetor. Thus, the generation of fuel vapor in the diaphragm-type carburetor can be restrained.