On Jan 21, 7:19 am, "Allen" wrote:
I think you are making this waaaay to complicated. The volume of air going
through the venturi remains the same as you climb but the amount of oxygen
(the component needed to burn the fuel) decreases. The volume of air
remains the same so the fuel drawn out of the float bowl remains the same.
There is less oxygen so the mixture become rich.


More properly, the weight of the air decreases. Oxygen still
makes up 21% of the air.

Dan