LESSON TWENTY-SIX

HOW TO START AND CONTROL AUTOMOBILE POWER PLANT

Q. Before starting automobile engines, what precautions are necessary?

A. The motorist should make sure that there is plenty of gasoline in the tank and that it is turned on so it will flow to the carburetor. The radiator should also be filled with clean water and the oiler must also receive attention. The gear shift lever is placed in the neutral notch and the emergency brake hand lever is locked in such a way that the brakes are engaged. The spark lever on the steering wheel is set at a retard position and the throttle or gas lever is slightly advanced. The switch for the ignition system is then placed in its active position.

Q. Why must radiator be filled?

A. It is imperative that there be enough water in the cooling system or the engine will soon become overheated.

Q. Why must oil supply be inspected?

A. If an automobile engine is run for any length of time without lubricant it will be seriously damaged, so before attempt is made to start the engine for a day's service it is well to see that there is an adequate supply of lubricant in the oiling system.

Q. Why must gasoline be turned on at the tank?

A. At the tank end of the pipe line conveying gasoline to the carburetor will be found a shut off valve as indicated at Fig. 246. If this valve is closed no fuel will reach the carburetor so it is important to open it up or see if it is opened before attempting to start the engine.

Q. Why must switch be closed?

A. The switch must be closed or placed in operative position so the current can flow to the spark plugs depended on to ignite the fuel in the cylinders.

Q. If both battery and magneto ignition are provided, which is preferable to start on, and why?

A. The switch lever should be placed on the battery side of the switch as indicated at Fig. 247-A because it is easier to start an engine with a battery spark than it is from the average magneto.

Fig. 246-Typical Fuel System Showing Shut-off Valve at Tank.

With a battery the current is always available whereas it must be generated by revolving the magneto armature if attempt is made to start on the magneto. Some forms of magneto, notably those of the true high tension type, generate current enough to ignite the gas even if the armature is turned slowly. Magnetos of the transformer coil type do not generate current enough at low speeds provided by hand cranking to furnish positive ignition. Most car manufacturers, therefore, advise starting on the battery.

Q. Where should speed change gear lever be, and why?

A. The gear shifting lever should be in neutral position, as shown at Fig. 247-B, because if it is in one of the speed positions so that a pair of gears are meshed it will not be possible to turn the engine without moving the car. If the engine is a type that is easily started it may pick up its explosions quick enough so the car will move as soon as the engine starts.

Q. Why should spark lever be retarded?

A. The spark lever should be placed in the retard position, as shown at Fig. 247-C, because an advanced or early spark will pro

Fig. 247.-Position of Switch, Gear Shift and Motor Control Levers on Overland Car Before Starting Engine.

duce a back kick or preignition in the cylinder that will tend to reverse the crankshaft rotation and bring the starting crank forcibly in contact with the operator's arm or wrist.

Q. How should throttle control lever be placed?

À. The throttle control lever should be partially advanced in order that a supply of gas be drawn into the motor cylinder as the engine is cranked over by hand. The position of the throttle lever relative to that of the spark control on the Overland car is outlined at Fig. 247-C.

Q. How should motor be cranked?

A. The method of cranking the motor properly is outlined at Fig. 248. In the first place the starting handle should be grasped in the hand as indicated in the inset A because if held in this manner it will be pulled out of the hand if the motor should back fire due to an advanced spark lever and early explosion. In cranking the motor the starting handle should always be pulled up with a quick, sharp movement. One should never push down on a starting handle, because when one pulls if there is a reversal of crankshaft motion

Right way of cranking the motor

A

Wrong way of cranking the motor

Fig. 248.-Proper Method of Grasping Hand Starting Crank in Order to Avoid Injury Due to Backfire.

the starting crank will be pulled out of the hand, whereas if one pushes down a back kick is apt to injure the arm or wrist.

Q. Describe process of "tickling" carburetor and explain why this is sometimes necessary.

A. After a carburetor has been standing for a time a certain portion of the liquid in the float bowl is apt to evaporate or leak out and the level of fuel will be so low in the standpipe that gasoline will not be drawn out to start the motor. In order to insure having

sufficient gasoline in the mixing chamber it is customary to depress the float several times with a small priming pin or plunger protruding through the float bowl cover. This process is commonly called "tickling" the carburetor and causes a portion of the gasoline to overflow the standpipe so when the air is sucked through the mixing chamber it picks up some of the liquid fuel and a rich mixture is produced that makes starting easy. Depressing this pin is sometimes called "priming" the carburetor.

Fig. 249. Showing Various Positions of Motor Control Levers for Different Engine Speeds.

Q. What is another method of priming the engine with fuel? A. With most types of motors, starting will be considerably facilitated on a cold morning or after the car has been standing for a time if gasoline is introduced directly into the cylinders through the priming cocks or compression relief cocks on the cylinder heads.

Q. What is the first step after the engine starts, and why is it necessary?

A. As soon as the engine starts, the throttle lever should be