Newps wrote:
On the 470's, in cruise, you give it whatever carb heat gets you a
carb
temp of 40-45F. Running at full carb heat makes no sense whatsoever.

Why not? Using full carb heat would seem to promote better mixture
distribution. The reduced charge density would allow you to run a
higher manifold pressure for the same mass flow, reducing the pumping
loss for a given power setting.

Obviously aggressive leaning probably to at least peak would be
desirable, although who knows where the non-instrumented cylinders
would be running.

I'd be a little concerned running partial carb heat as there would
possibly be a considerable temperature gradient in the air intake
system, given how the carb heat is crudely modulated with that
humongous flapper valve. In other words, some cyls might get a hot
mixture, and some might get cold mixture.

This is assuming the purpose of all this is to reduce the fuel
consumption to get maximum endurance or range under low power settings.
I don't think cyl temp would be a limiting factor.

I don't normally fly my 172M this way (w carb heat always on), but if
it was a question of making it or not, I'd sure use it.'

Thoughts of others?

Most pilots don't know how to get the absolute maximum range or
endurance out of their aircraft.