Quote:
Originally Posted by Christ
I think you did indeed miss something.
...the standard practice is that LessVacuum == MoreLoad, hence: more fuel injected to compensate.
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Less vacuum does not = more load, it simply = greater air flow via less throttle plate restriction, or lower rpm's. Though the two happen simultaneously in most cases.
Load is based upon resistance to rotation at the output shaft of the engine whether due to a hill or added weight, or in the case of the generator which was used for the example earlier on in this thread, the added magnetic resistance to rotation due to a greater electrical demands of the load.
When the rpm's of the generator are reduced due to the above, the engine rpm's are reduced as well, which causes the governor to lessen its resistance to the spring which controls the throttle plate in the carb... this allows the plate to be pulled to a more open position and allows more air flow through the venturi, and thus a greater flow of fuel due to the increased air flow at the fuel port. This increase of available fuel and air in the chamber allows for an increase in RPM's, thus increasing the output power of the generator head, in addition to causing the governor to again over power the spring to the throttle plate.
If you plug the opening to the carb with your hand, the air flow drops, vacuum spikes, and the engine draws too much fuel and dies both from lack of oxygen and a flooded condition. This is also why a carburetor engine with a vacuum leak runs too lean.
Dipstick