Fig. 30.—Pump-fed Carburetor
With Two Fuel Nozzles
The carburetor shown in [Figure 30] is similar, but has a bowl and spray nozzle for gasoline, to use in starting. It is also provided with a heating jacket through which hot water or hot gases may circulate.
In many cases the fuel is heated before reaching the carburetor. This is done by coiling the feed pipe around the exhaust pipe or putting it in a jacket through which hot water circulates.
Another device sends the mixture through a chamber heated by the exhaust, as shown in [Figure 31]. [Figure 32] shows an arrangement in which the mixture passes through a jacket around one branch of the exhaust pipe. By means of a switch valve, A, more or less of the exhaust gases may be permitted to flow through this branch, so that the mixture may be heated to any desired degree.
Fig. 31.—“Hart-Parr” Mixture Heater
All of these heating devices are so arranged that the heat is under the control of the driver, which permits him to heat the mixture as much as he judges to be necessary. Enough heat must be used to prevent the fuel from condensing; but too much heat will cut down the efficiency of the engine because it will cause so much expansion of the mixture that a cylinderful of it will not produce the maximum power.
Fig. 32.—“Twin City” Manifold