Carburetor ICING Jerry/MT

Gotta disagree with your statement: "Fuel additives don"t help with carburetor icing. They only work to keep the water in the fuel bowl,tanks,and sediment bowls, low spots, etc from freezing and blocking the passages."

Fuel additives DO help, at least to a certain degree, with the internal icing in a carburetor that is the actual cause of poor running, as apposed to the visible ice on the OUTSIDE of the carburetor.

The problem is that internmal carb icing is not caused by water in the fuel. It"s caused by ambient humidity the same thing that causes the external frost to form. The lowered static temperature that results from the high velocities in the carb plus the evaporative cooling of the fuel cool the metal well below ambient temperature.
The same type of icing (less the evaporative cooling effect of the fuel)is prevalent in the inlet and on blades and static structure near the compressor face of gas turbine engines and for the same reason; high ambient humidity. That"s why bleed air from warm parts of the compressor are ducted to the vanes and in some cases the spinners to preclude ice formation.

Water in the fuel is a whole other issue.