The Bing meters fuel with the interaction of the needle and the main jet. At
full
throttle the needle has been lifted clear of the jet. Jet size (bore) at
WOT determines fuel volume and is sized to flow a little extra at WOT providing
richer mixture for climb. Upon reaching cruise and reducing throttle the needle
decends part way into the jet bore, constricting the fuel delivery to cruise
rates (up to 4000ft). Higher than that the diaphragm needs a little help
to lower the needle in the jet. The Hacman changes the pressure (vacuum) on top
of the diaphragm thus lowering the needle and leaning the mixture.
Id be awfully cautious about messing with the 914 mixture as it is a
turbo-normalized
engine.
Creighton
Sent from my iPad
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