thanks for the tip i just ordered some of the silicon bronze
i test welded on the 20g that i was adding and i welded that no problem at 50 amps
i will play around after the other wire gets here
hoping to not use any bondo at all
SilBr requires far less heat than ER70 wire. You don’t actually melt the parent metal, just the wire. It’s really a brazing technique which makes it far better for this type of work. That plus the filler will not rust. Ever.
To do this modification, you need to chemically strip the tank outside bare where you will TIG. Plus, the interior must be absolutely rust free and chenically spotless. Any contamination will create porosity in the welds which will cause leaks.
The “right way” to do this is time consuming, a tad tedious, but easy enough. Make 1” marks along the lip. Every inch, use a cut off wheel and nip the lip. You’ll now have 8-12 1” “tabs”.
Start in the center and use a flap disc, grind the center tab back. Wipe with acetone. Tack dead center of that 1” section. Then at either end of that section. Skip the next tab and repeat the process on the next one. Grind, clean, 3 tacks. Do this from center to end, then center to other end. Then come back and work from center out on remaining tabs.
Skipping allows the metal to cool. In about 3 hours you’ll have the lip ground back, about 40 tacks, and no warpage.
Then, a single stitch weld 1” long with filler. Start and stop on tacks. Let the tank cool, weld another inch. Let cool. Repeat until filled and complete. Then grind and shape until you’re happy.
Take your time. Clean well constantly. Low heat. Done. A pro will charge you $500 minimum to do it “right”.
