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.

I find that I can run my Cherokee's O-360 LOP quite effectively using full
carb heat. Attempts to do so without carb heat lead to unacceptable engine
roughness. With the carb heat on, I can reduce the RPM down several hundred
RPM from peak RPM with good smoothness. Without the carb heat, the RPM
peaks as the mixture gets leaner, then as the RPM begins to drop the engine
gets progressively rougher.

I have not run the engine LOP for any appreciable length of time as I have
no CHT or EGT instrumentation. I have done it for a minute or so to see if
it is possible.
--
Aaron C.