[.041 Safety Wire]

AutoLean position for throttle would be nice to have, but still, right now, when using flight manual figures for minimum specific consuption, it works !

For the P-38J figures from the manual are

20000ft 31 manifold 1700 RPM
10000ft 29 manifold 1600 RPM

Try these, you should see a sigifnicant difference in fuel consumption (about only 25% of what you use at military power !)

Autolean along with autorich are functions of the mixture control lever. The throttle is either open or closed. Open means more manifold pressure closed means less. Another function of the autorich setting or power enrichment valve is to add more fuel during high throttle settings. In this case the additional fuel helps with the cooling of the cylinder head. Likewise leaning will cause a rise in cylinder head temperatures. Again it is the lowering of manifold pressure that accounts for the lessened fuel consumption. Just lowering rpm,s which is accomplished by adding more pitch to the prop blades actually places more of a load on the powerplant. A good way to think of this is if you are in an auto with the throttle set in one position. If the car starts up an incline, as the powerplant is loaded the rpm,s will decrease because of the additional load but fuel consumption will actually rise . You need to close the throttle plate in order to conserve fuel.