An improvement in a cast head for a high performance internal combustion engine having a flat mounting surface for each of several in-line circular piston areas, a wedge type combustion chamber extending from the head mounting surface and defined by a flat quenching surface and a concave, contoured wedge-shaped cavity forming surface. This wedge-shaped cavity tapers outwardly from the quenching surface between a shallower portion adjacent the quenching surface to a deeper portion in which the valves are located. The cavity forming surface of the deeper area of the combustion chamber being provided with a general contour defined by two parallel intersecting, truncated cones generally concentric to the two valve openings in the wedge-shaped combustion chamber with a gradually contoured surface section between the cones at the deeper area of the combustion chamber and a velocity increasing protuberance in the combustion chamber at the shallower portion of the cavity which protuberance includes a curved edge portion of the flat quenching surface, which edge portion extends inwardly of the wedge shaped cavity toward a position between the two valve seats and a built up mass of cast material sloping from the curved edge of the quenching surface toward the valve seats to guide gases from the combustion chamber through the exhaust outlet primarily and, to a lesser extent from the intake inlet into the combustion chamber. This mass of material increases velocity through the exhaust port during the engine exhaust cycle.