Silver soldering cast iron demonstration featuring a custom exhaust system.
Watch as Josh Colson from Auburn Muffler and Auto Repair in Auburn, Washington, uses SSF-6 Silver Solder to braze a cast iron flange to aluminized steel tubing to create better air flow. The parts featured were removed from a 2000 Mazda RX7 turbo.
Josh first cut off the restrictive cast iron outlet, then replaced the outlet with 3 inch piece of regular muffler shop aluminized tubing. Using an oxyacetylene torch, Josh silver soldered the aluminized tubing to the cast iron exhaust at only 1150°F.
Prior to silver soldering the cast iron parts, Josh pre-cleaned both metals to remove impurities, then grinded the edges of both metals to create a gap and ensure a strong bond.
Josh aimed his torch toward the cast iron while preheating because the cast iron is thicker than the aluminized steel. it is important to preheat the metals at the same pace to avoid overheating or melting the softer metal. This was quite a large piece of cast iron, so preheating was an important step before soldering.
We recommend using an oxyacetylene torch for soldering large or thick pieces of metal. Brass tips and propane torches provide inadequate heat when soldering large metal masses.
Troubleshooting tip: If the rod balls up and falls off the part, this is an indication that the base metal is too hot and the rod is not bonding. Simply pull back the torch a bit to drop the temperature rapidly, or you can switch out the torch tip like Josh did. If the overheating continues, turn down the oxygen on your torch.
After silver soldering the cast iron parts, Josh allowed the parts to cool naturally before finishing the metal.
Josh finished soldering the cast iron part, grinded it down, repainted it, and re-installed it.
Another happy Muggy Weld customer! Thanks, Josh, for sharing your innovative use of SSF-6 Silver Solder.