is one brand,
but most local welding shops will carry some version of the
stuff. I used it to braze my intake tubes to 1/4" plate, but
I have no idea whether it will stand up to the intake pulses
& vibration with the engine running. I can tell you that
the stuff isn't the magically easy to use stickum that it
seems to be, when you're watching the carnival barker at SNF
The stuff I used was marginal on thick stuff with a propane
torch (might not be a factor with the heat exchanger). You'll
almost certainly need a wood handled stainless steel brush to
free the corrosion on the base metal while the torch is
applied to the molten brazing material.
Have you
thought about hitting Barry up to take a look at it? ;-)
Charlie