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The Motoe Car Gasoline Engine

system, feed, tank, engines, carburetor, air and fuel

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THE MOTOE CAR GASOLINE ENGINE The four cycle engine is the only type used for motor car engines, and all of them have from four to twelve cylinders, or twin sixes as the latter are called, and these are of the V type.

About the Fuel Feed System.—Kinds of Feed are three kinds of fuel feed sys tems used on motor car engines, and these are (1) the gravity feed, (2) the air pressure feed, and (3) the vacuum feed system.

The Gravity Feed System—As in stationary and motorcycle engines a gravity feed is sometimes used, in which case the tank is placed under the front seat of the car, when it is, of course, higher than the car buretor.

The Air Pressure Feed this system the gasoline tank is placed back of the rear axle and it is lower than the carburetor. Air is pumped into the tank either by a hand pump or by a pump driven by the engine, until it is under three or four pounds pressure, when the compressed air forces the gaso line into the carburetor. The scheme is shown in Fig. 48.

The Vacuum Feed System.—The supply tank in this system is likewise placed back of the rear axle and below the level of the carburetor.

The gasoline is drawn from the supply tank into a small fuel tank, which sets above the carburetor, by the vacuum produced by the action of the pistons in the cylinders. The fuel tank has a float with a valve on it which cuts off the gasoline from the supply tank when the former is partly filled.

The fuel tank is connected to the carburetor and the gasoline flows into the latter by gravity. This system is shown in Fig. 49.

The Use of the carburetor is identical with the one described in the beginning of this chapter. The amount of fuel mixture admitted into the cylinders is controlled by a hand throttle and a foot accelerator, both of which are connected with and operate the throttle valve in the carburetor.

The Ignition System.—The jump-spark system is the only type used on motor car engines; but there are three kinds of jump-spark apparatus and these are (1) the battery and spark coil system, (2) the high, tension magneto, and (3) the circuit breaker, spark coil system.

The battery and spark-coil system, which is the same as that used in stationary and motorcycle en gines, has all but been displaced by the magneto and the newer circuit breaker spark coil systems. Many

motor car engines are equipped with this system alone while some of the better engines have both it and the high tension magneto, the last named also hying been explained in Chapter III.

In the Circuit Breaker Spark-Coil ignition sys tem a spark coil made exactly like the battery spark coil is used, but it has no vibrator on it.

The circuit breaker is formed of a cam which has as many corners on it as there are cylinders to be fired. This cam is fixed to a shaft which is geared to the camshaft of the engine and this takes the place of the vibrator, in fact it acts exactly like the inter ruptor on a magneto.

The distributor is the timing device and it is made like the one described in connection with the mag neto. The contact arm is rotated by the same shaft that carries the cam of the circuit breaker. The spark-coil is energized by a storage battery, which also delivers current for the electric starter and the electric lighting system. Fig. 50 is a diagram of the system.

Engine Cooling Systems.—Since only a small amount of water can be carried to cool the engine it must itself be cooled by some means, and this is done by a radiator.

A radiator is built in one of two different ways, namely, (1) with small vertical pipes through which the heated water flows and which are cooled by the air blowing on them, or (2) with horizontal pipes around which the heated water flows and which are cooled by the air blowing through. them. The first kind is called a tubular radiator and the second is called a cellular radiator, and these are shown at 4. and B in Fig. 51.

There are two ways in which the water in the radi ators and the jacketed cylinders is kept circulating, and these are by (1) system and (2) the pump circulating system. In the former the water is kept circulating by the heat itself in exactly the same way as in the cooling tank system described in Chapter III. In the latter it is forced through the radiator and the jacketed cylinder by a rotary pump. _ About Lubricating the splash and force feed lubricating systems which are used for oiling motorcycle engines are likewise employed for oiling motor car engines.

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