In rec.aviation.owning nrp wrote:
: Max Conrad (ferried Pipers all over the world in the 40s and 50s) ran
: fully leaned & with full carb heat when he was in his max range mode.
: Do you know of any reason not to, assuming a low power setting? It
: would improve the mixture distribution, something the O-470s are
: notoriously poor at. It would also reduce the inlet air density,
: allowing things to operate with less pumping loss.

Unless the CHT's get too high in that configuration (causing poor valve
cooling and cylinder badness), there's not much that says it's bad except:
- No filtration of the air with carb heat. Shouldn't be a big deal in cruise (unless
you have a *really* dirty cowling).
- If flying in cold enough weather, you could get carb ice when normally ice crystals
would flow through unmelted. (I generally don't like to use carb heat until I know
it's necessary)
- Sudden power requirement will cause the engine to falter... get used to a quick red
knob, then throttle.

The real disadvantage of the arrangement on my fixed-pitch plane is 65% is
only obtainable at that mixture up to about 7000-8000'. "Best power" of 50 ROP will
get you 75% or so at that altitude.

-Cory

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
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