In article jy67f.6582$%A1.1101@trndny01,
George Patterson wrote:

Cub Driver wrote:

(Must be more to carb heat than that. Bypassing the filter ought to
increase performance in every instance, or at least never decrease it.

Yes.

But pulling carb heat on, in the Cub, does definitely cause a decrease
in power.

The heat normally creates a rich mixture, which causes a decrease in power.

George Patterson
Drink is the curse of the land. It makes you quarrel with your neighbor.
It makes you shoot at your landlord. And it makes you miss him.

If the carburetor attach flange nuts are loose, the mixture will be very
lean, due to air leaks around the base. Applying heat will enrich the
mixture, possibly correcting a too-lean condition. I have seen a few
planes with loose carburetor attach nuts.