| 摘要 |
PURPOSE:To facilitate the manufacturing of a helical intake port, by making a casting wooden core capable of split into an upper and a lower sectins, to provide a branch passage not having a central portion and provide a vortical passage and an inlet passage in casing a cylinder head and by thereafter drilling the central part of the branch passage section to open it through. CONSTITUTION:A casting two-split wooden core for providing a branch passage 21a not having a central portion Q and connected to the side wall 16 of an inlet passage A, a branch passage 21b connected to the end E of a vortical part B, an inlet passage A and the vortical part B is prepared to cast a cylinder head (not shown in the drawing) having a helical intake port 6. After that, the central section Q is drilled to provide a circular hole 24, in which a rotary valve 25 is fitted. According to this method, the helical intake port 6 is easily manufactured at low cost. |
