Method for producing a rocker arm for use in an internal combustion engine

摘要

A method for casting a rocker arm made of light alloy for use in an overhead cam shaft type valve operating mechanism of an internal combustion engine, which rocker arm includes a thick-walled bearing section to be fitted on a rocker arm shaft and is integrally provided with a wear-resistive piece having a protrusion on its rear surface and adapted to abut a cam. After molten metal has been injected under pressure into a metallic mold for the rocker arm, a secondary pressurizing force directed in the direction of an imaginary center axis of a rocker arm shaft is exerted by means of a pressurizing rod. In the metallic mold for the rocker arm, a sprue is provided close to the position where the wear-resistive piece is disposed with respect to the position where the bearing section is formed, and the direction of the sprue is directed towards the position where the wear-resistive place is disposed.