Abstract: A unitary block of steel is formed into a manifold by a feeder bore that is intersected by one or more common branch bores. The common brach bore includes a first branch and a second branch which extend along the common branch bore axis in opposite directions from the feeder bore. The first branch is intersected by a first stem cavity and the second branch is intersected by a second stem cavity, and the valve stems are located in these cavities. In this way, the manifold block is formed by boring operations instead of by casting, the flow of gas through the branches is unimpeded by obstructions or offsets in the flow path.