Warbird automixture

[KevinB]

Can anyone give me the "cliffs notes" version of how the auto-mixture system works on a typical warbird?
For example P-51d:
Are there limits of pressure altitudes where it works/ doesn’t work? And does one have to revert to manual leaning by recommended procedure by use of egt or cht possibly?? outside the limits? Is there a rich and lean of peak setting within the automixture auto setting?

Thanks,

[GADGET]

It is not a hard system to do.

Optimal fuel combustion depends on the amount of air/fuel quantity, called stequiometric when no fuel nor oxigen are wasted and their proportion is optimal.

To obtain the stequiometric proportion it is required to know the amount of oxygen available and add enough fuel to keep the balance. The amount of oxygen can be obtained be knowing the static presure of the air that sorounds the aircraft, via a simple pressure metering device (anaerobic capsule for instance).

This way a mechanical computer can be built and tuned to give optimal performance at any altitude, allowing only the right amount of fuel to reach the cilinders.

Hope this simple explanation might be useful to you.