I am using a Miller Syncrowave 250. I have quite a bit of experience in aluminum, and I have welded these radiator shells before, but I seem to struggle with it. Thicker aluminum is no problem for me. Should I use an Argon/Helium mix? I know it really needs to be cleaned well and possibly use a stee...

No question that this is aluminum. In 1928, Chevrolet made aluminum and steel grille shells, no SS that I am aware of. I can get to the backside for cleaning without a problem. The shell I have to work on needs some modification, so I'm going to have to cut and weld in several areas.

I do vintage vehicle restorations and I have been asked to repair an aluminum radiator shell for a 1928 Chevrolet passenger car. The aluminum is about .040" thick. Can you give me some tips on butt-welding this type of aluminum, I.E. type of shielding gas, rod, procedure, etc.?
Thanks!