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Q. What color is the exhaust flame when there is too much gasoline?
A. If the exhaust gases are reddish in color, it indicates a surplus of fuel.
Q. What color is the exhaust when there is too much air in the mixture?
A. The exhaust flame is yellow in color when there is an insufficient amount of gasoline in the mixture.
Q. What is the advantage of water-jacketing a carburetor?
A. It is very desirable to water jacket the float bowl of the carburetor and the mixing chamber and to pass some of the cooling water from the cylinders through this jacket. The heat assists in vaporizing the liquid and makes more uniform mixture proportions.
Q. Why is it desirable to supply hot air to a mixture?
A. In many cases the main air supply is taken from a point near the exhaust manifold so that only heated air is drawn into the carburetor. The advantage of using heated air is that it is more suitable for use with low grade fuels which do not evaporate readily than cold air. The warm air tends to vaporize the liquid, whereas cold air tends to condense the vapor.
Q. How are low grade fuels utilized with conventional vaporizers?
A. There are two methods of using carburetors of the design adapted for gasoline with the lower grade fuels such as kerosene. These are outlined at Figs. 72 and 73. In the former, in addition to pre-heating the fuel by a water jacket around the float bowl, a spray of water is injected into each gas charge. The function of the liquid is to turn into steam from the heat of the explosion, liberating oxygen which combines with the surplus carbon and tends to make combustion more perfect.
At Fig. 73, a carburetor intended for use with either kerosene or gasoline is shown. The supply pipes from both gasoline and kerosene tanks are led to a common fitting or valve which can be turned so that either liquid will be supplied the float chamber. When gasoline is used, the mixture flows directly to the cylinder because the supplementary throttle is moved in such a position that the
Fig. 73.-Sectional View of Woolsely Two-Fuel Carburetor Which is
Adapted to Vaporize Either Gasoline or Less Volatile Fuels Such as Kerosene.
mixture is not forced through the fuel gas vaporizing coil, but passes right into the cylinder through the main throttle and gas outlet. When kerosene is employed, however, it is necessary to heat the vapor to insure thorough vaporization. The supplementary throttle is then moved out in such a way that the fuel gas must pass through the vaporizing coils which are surrounded by the hot exhaust gases before they are drawn into the cylinders.
Fig. 73a.—Diagram Showing Method of Connecting the G. C. Kerosene Vaporizer to Conventional Four-
on Gasoline if Desired.
Q. Describe the G. C. kerosene vaporizer, and explain its action.
A. The general arrangement of parts of G. C. kersoene vaporizer is illustrated at Fig. 73-a. This device has been in use in England for nearly two years and has been applied with success on commercial vehicles, motor boats and stationary engines. An advantage is that this type of kerosene vaporizer does not interfere in any way with the design or construction of the motor which retains the usual gasoline carburetor. This is employed for starting purposes, and the engine is run on gasoline until sufficient heat is obtained to va
porize the heavy fuel. The desired temperature for vaporizing the kerosene may be attained after motor operates five or six minutes. As the heavy fuel mixture is conveyed to the intake manifold above the regular form of carburetor, it is possible to use either fuel independently and run the motor on one fuel should the supply of the other become exhausted.
The G. C. vaporizer replaces the conventional muffler, and the exhaust gases are led to it from the motor, so the heat usually wasted is utilized for aiding in vaporizing the heavy fuels. The exhaust gases pass through the central portion of the vaporizer and during their passage they heat up a triple layer of small fragments of cast iron through which a horizontal pipe extends containing the fuel to be vaporized. Atmospheric air is drawn through the vaporizer at the same time from another opening, and as this mixes with the kerosene vapor, the cylinders are fed with a homogeneous gas. The amount of kerosene entering the vaporizer is automatically regulated by the motor suction and the supply increases in proportion to the motor speed because the degree of vacuum in the cylinders depends on the amount of throttle opening. The kerosene supply pipe goes to a float chamber communicating with the vaporizer by an independent p pe. The mixture from the vaporizer goes to the intake manifold, through a long fuel supply pipe, the motor end of which is fitted with an auxiliary air mixing valve and a throttle for regulating the amount of gas going to the cylinder.
The adjustments are very simple, and once the vaporizer is installed it is claimed that it requires no further attention. If the motor shows evidence of smoking, the adjustment A of the auxiliary air valve is moved in the direction of the arrow D. If the engine back-fires because the mixture is too thin, the adjusting screw A is screwed in the direction of C. The low speed adjustment is obtained by the screw B, which is moved in the direction a if the motor smokes and toward b for back-firing. The amount of kerosene entering the vaporizer-silencer may be regulated by moving the screw E on the float chamber in the direction e for smoking, and in direction f if the motor back-fires.
It is claimed that this device permits the use of other fuels besides kerosene, as it has operated successfully on alcohol, heavy petro
Fig. 74.-Defining Method of Utilizing Kerosene in Two-Cycle
Motors by Direct Injection in Cylinder.
leun, and very low grade kerosene, commonly called "distillate.”' When properly adjusted, it is advanced that the consumption of kerosene is about 20% less than gasoline needed for the same power output. To start a motor employing this system it is necessary to close the kerosene throttle entirely and to start the motor on the gasoline carburetor and regulate its speed for five to ten minutes by the gasoline throttle at the lower portion of the intake manifold. When it is desired to operate on kerosene, the gasoline throttle is gradually closed and the kerosene gas controlling throttle is gradually opened until the motor is running on the kerosene mixture.