Here is a epoxy thats made for gas tanks, (Magnum Instant Gas Tank Repair 4.59$)
it seems it would work on carbs jut fine also?
I think it could work for older well plugs that leak.
"Features & Benefits:
No need to remove or weld leaking fuel tanks. Special steel filled formula works in the presence of gasoline and diesel fuel. Use like putty but hardens like steel. Instantly plugs pin holes and seam cracks.
A two-part epoxy putty stick that repairs leaks, holes and cracks in metal
Plugs small holes, seams or cracks on any gas tank instantly, without welding or removal of tank
Repairs cracks and breaks in tanks and drums, plumbing and pipe repair
Works in the presence of gasoline and diesel fuel"
