Abstract: Investment casting of an engine part using a pair of core members having respective opposed faces spaced apart by a first distance, a face of a first core member of the pair being provided with one or more protrusions thereon and a face of the second core member of the pair being provided with one or more respective open recesses therein, each protrusion facing a respective open recess, wherein during a casting procedure the first and second core members are maintained positioned relative to each other so major portions of the opposed faces of the first and second core members assume mutual spacing equaling a corresponding predetermined thickness of a portion of a resulting cast wall of the first distance; and at least a head portion of the protrusion is located within the respective open recess to define a minor portion of the resulting cast wall.

Abstract: Investment casting of engine part defined during casting by pair of core members having respective opposed faces, major portions of opposed faces being spaced apart by first distance corresponding to predetermined thickness of a portion of resulting cast wall, face of each opposing core member which face each other being provided with respective open recesses, each protrusion on first core member facing a respective one of second core member, wherein during part of casting procedure first and second core members are maintained positioned relative to each other so major portions of the opposed faces of first and second core members assume mutual spacing equaling corresponding predetermined thickness of portion of resulting cast wall; and at least head portion of protrusion on first core member is located within respective open recess in second core member, such that respective protrusion and respective open recess define respective minor portion of resulting cast wall.