Bucc, the stuff that you are calling “silver solder” , what is it? It’s surly not what is commonly called silver solder. What I know as silver solder, is hard solder, melting point at a red heat..

Joe B

OK , thanks guys… always trying to learn here.
I was befuddled by the “silver solder” thing, because in common usage silver solder is a high temp (red heat ) hard solder. Wonderful stuff , joints as strong as brazing. I looked up the Oatley “silver safe flo solder” .. It is a low temp (420 – 460*F) soft solder designed to replace the old lead- tin alloy plumbing solder. The data sheet from Oakley says that it contains less that 2 % silver and no lead. It does not say what the primary metal in the alloy is. I suspect that there is tin and bismuth. Bismuth is the base for the various very low temp melting alloys like Cerrobend… you might recall the trick metal teaspoon that melts in your cup of coffee…bismuth .
As for sticking to the aluminum or pot metal of the carb housing, the lead-tin solders will stick but with great difficulty and scrupulous cleaning. I guess the the same would be true for the Oatley silver stuff.
The go to metal repair for aluminum or pot metal is the low temp solder sticks that the guys sell and demo at the flea markets, soldering alum beer cans. again takes refined technique and cleanliness, but will do good strong repairs.

And, in the way of schooling … what is Belzona?

Joe B .