Always wear proper eye protection. You should buy some #3 or #4 shade welding/cutting goggles. Sunglasses are not acceptable eyewear. Brazing isn't good at filling large gaps. Parts should fit as close a humanly possible. A close fit will always pay off. A professional oxyacetylene set-up with a welding tip is the best heat source to use. MAPP gas+Air takes forever to heat. You may also use a TIG torch for TIG brazing, but that is an altogether different set of skills. Use flux-coated brazing rods if you can find them. Use a slightly reducing flame for brazing. That means the flame is slightly fuel-rich. if you have the ability to tack-weld the parts in place before brazing, do so. For example, if you have a small arc welder. This is generally a lot easier than jigging and clamping the two parts down. Brazing takes two hands. Apply heat to the PART and not to the FILLER. Keep the filler out of the flame until the part has reached the proper temperature. Apply heat gently and evenly, and don't overheat. If parts start fuming excessively you're too hot. Don't heat a single spot for a long time, unless you have a large joint to fill. Most brazing alloys begin to flow when the part to be brazed is light cherry-red heat. Once the rod begins to flow, hold the heat for about a second and a half to ensure good fusion, then draw the flame ahead along the joint. Apply more filler as needed, but the brazed area should flow around to follow the heat. Don't go overboard with the filler. Get Practice. Hope this helps.