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Pulsa-Jet Carburetors
The Pulsa-Jet is a full carburetor incorporating a diaphragm type fuel pump and a constant level fuel chamber. The fuel tank, the fuel pump and the constant level fuel chamber serve the same functions as the gravity feed
tank, the float and the float chamber of conventional “float type” carburetors.
This new design makes it possible to obtain just as much horsepower from the Pulsa-Jet carburetor as is obtained from more complex “float type” carburetors. This is due to the fact that the Pulsa-Jet provides a constant fuel level directly below the venturi.
Very little fuel “lift” is required to draw gasoline into the venturi. The venturi can be made larger, permitting a greater volume of fuel-air mixture to flow into the engine with a consequent increase in horsepower.
Vacuum created in the carburetor elbow by the intake stroke of the piston pulls cap A and pump diaphragm B inward and compresses spring C. The vacuum thus created on the “cover side” of the diaphragm pulls gasoline up suction pipe S and under intake valve D into the pocket created by the diaphragm moving inward.
When engine intake stroke is completed, spring C pushes plunger A outward. This causes gasoline in the pocket above the diaphragm to close inlet valve D and open discharge Valve E. The fuel is then pumped into fuel cup F.
On the next intake stroke the cycle is repeated and this pulsation of the diaphragm keeps the fuel cup full. The venturi of the carburetor is connected to intake pipe which draws gasoline from the fuel cup F.
Since a constant level is maintained in the fuel cup, the engine gets a constant air-fuel ratio no matter what fuel level exists in the main tank.
From this point on, the carburetor operates and is adjusted in the same manner as is the Vacu-Jet carburetor except that the fuel tank does not have to be half full as in the Vacu-Jet. It can be full or almost empty and the adjustment will be the same since the fuel level in the small cup is always the same. There are no valve checks in the fuel pipes. The flaps on the diaphragm serve as valves.
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