U.S. Patent Specifications

The method of making a ring‐like flexible valve seat element for an internal combustion engine of the poppet valve type which comprises providing a suitable frusto‐conical shaped blank having a counterbored aperture extending therethrough with the large end of said aperture which also forms the seat proper opening into the large end of the blank and an annular tapered groove converging towards its bottom in the large end of the blank in spaced relation with said counterbore and undercutting a portion of the blank radially inwardly of the groove, the outer side wall of said groove diverging toward the surface of the blank, contracting the portion of the blank externally of the groove to only partly close said groove, and subsequently machining the blank to the desired final shape.