Ford Manual
For the convenience of the driver in adjusting the carburetor. After the new car has become thoroughly
worked in, the driver should observe the angle of the carburetor adjusting rod at which the engine runs
most satisfactorily. In cold weather it will probably be found necessary to turn the adjusting rod one-
quarter turn to the left, particularly in starting a cold engine. As gasoline vaporizes readily in warm
weather, the driver will find it economical to reduce the quantity of gasoline in the mixture by turning
the adjusting rod to the right as far as possible without reducing speed. This is particularly true when
taking long drives where conditions permit a fair rate of speed being maintained, and accounts for the
excellent gasoline mileage obtained by good drivers.
What is meant by a "lean" and a "rich" Mixture?
Answer No. 44
A lean mixture has too much air and not enough gasoline. A rich mixture has too much gasoline and not
enough air. A rich mixture will not only quickly cover the cylinders, pistons and valves with carbon, but
will tend to overheat the cylinders, and is likewise wasteful of the fuel. It will often choke the engine and
cause misfiring at slow speeds, although at high speeds the machine will run perfectly. The mixture
should be kept as lean as possible without the sacrifice of any of the power of the motor. A lean mixture
will often result in backfiring through the carburetor, for the reason that the gas burns slowly in the
cylinder, and is still burning when the inlet valve opens again, which causes the gas in the intake to
ignite. A rich mixture is shown by heavy, black exhaust smoke with a disagreeable smell. Proper mixture
will cause very little smoke or odor.
How is the Carburetor adjusted?
Answer No. 45
The usual method of regulating the carburetor is to start the motor, advancing the throttle lever to about
the sixth notch, with the spark retarded to about the fourth notch. The flow of gasoline should now be cut
off by screwing the needle valve down to the right until the engine begins to misfire, then gradually
increase the gasoline feed by opening the needle valve until the motor picks up and reaches its highest
speed and no trace of black smoke comes from the exhaust.
Use care in adjusting the carburetor as turning the needle down too tightly will result in its becoming
grooved and the seat enlarged. When these parts are damaged it is difficult to maintain proper adjustment
of the carburetor. For average running, a lean mixture will give better results than a rich one.
Why does water clog the Carburetor?
Answer No. 46
The presence of water in the carburetor or gasoline tank, even in small amounts, will prevent easy
starting and the motor will misfire and stop. As water is heavier than gasoline it settles to the bottom of
the tank and into the sediment bulb along with other foreign matter. As it is difficult nowadays to get
gasoline absolutely free from impurities, especially water, it is advisable to occasionally drain the
sediment bulb under the gasoline tank. During cold weather the water which accumulates in the sediment
bulb is likely to---freeze and prevent the flow of gasoline through the pipe leading to the carburetor.
Should anything of this kind happen it is possible to open the gasoline line by wrapping a cloth around
the sediment bulb and keeping it saturated with hot water for a short time. Then the water should be
drained off. In event the water gets down into the carburetor and freezes, the same treatment may be
applied.
What makes the Carburetor leak?
Answer No. 47
The flow of gasoline entering the carburetor through the feed pipe is automatically regulated by the float
needle raising and lowering in its seat. Should any particle of dirt become lodged in the seat, which
prevents the needle from closing, the gasoline will overflow in the bowl of the carburetor and leak out
upon the ground.
When there is dirt in the Carburetor---what?
Answer No. 48
