The problem with brazing cast iron or steel that is subject to heating and cooling is that the brass expands faster that the cast as it heats and when it cools it contracts faster so that ultimately failure will occur. This may take minutes or years, An ony- acetelene torch is probably the most successful using a cast iron rod and preheating the part and letting it cool after the weld over a period of hours usually by packing it in hot sand. Spray welding might be the best, but I have had no experience with that method.
