block 10 a further at the second machining station a spark plug opening 28 a is drilled and tapped the cylinder block 10 a is moved to a third machining station fig9 where the piston chamber 26 a is subjected to a boring operation the sequence of the foregoing operations is illustrated in fig1 it should be appreciated that even though casting costs are relatively low as a result of wide as cast tolerances the material handling and machining costs combine to eliminate any savings in the casting operation by requiring the die caster to hold tighter tolerances particularly with respect to the flatness of the foot flange mating surface 20 and the fastener apertures a net savings results even though casting costs are relatively high the process according to this invention is illustrated in the flow chart of fig1 initially a die casting is produced having tight tolerances particularly with respect to flange flatness and surface finish as well as fastener hole diameters and true positional location of the diameters the preferred tolerance is approximately 0 006 inch for the mounting surface 20 the perpendicularity of the fastener openings 18 19 34 and 44 to the surfaces 20 36 and 46 is approximately 0 002 inch the true positional location of the fastener openings 18 19 34 and 44 is.