I am in the process of scratch building a two-cylinder, 90Degree "V" steam powered wobbler. The bores are 3/4 inch, and stroke is 1-1/4. Cast iron cylinders, brass pistons, steel frame. I have the cylinders, covers, pistons, connecting rods completed with no known issues. My question relates to the inlet and exhaust ports in the frame. I know how to align them above and below the cylinder pivots, however I am unsure about the lateral positions. As the port in the cylinder makes its arch, at what point along that arch, should the port in the frame align with it? I know the steam should ideally enter a bit before TDC. Is there a placement that relates to the crank? for example; the ports should be in full alignment when the crank is about 5 degrees before TDC. I hope I am making sense to at least some of the experts here.