3. Read and translate the text. Carburetor

The purpose of the carburettor is to provide a mixture of petrol and air for combustion in the engine. The mixture normally consists of one part (by weight) of petrol to fifteen parts of air, but this mixture varies quite considerably with temperature and engine speed. If there is a higher proportion of petrol the mixture is said to be “rich”. A higher proportion of air gives a “weak” mixture.

Very simply, the carburettor consists of a tube through which air is drawn, and a series of very small holes known as jets which break the petrol up into tiny droplets and pass it into the airstream in the form of a mist. The mixture of petrol mist and air is sucked along an inlet pipe (induction manifold) and then, by way of branches in the pipe, into each cylinder. A float chamber in the carburettor provides a small reserve of petrol for the jets and ensures an even supply.

The flow of air into the carburettor is controlled by a «butterfly throttle», which is a flap that can be opened and closed by operating the accelerator pedal in the car. Pressing the accelerator opens the throttle. This lets in more air, which in turn sucks more petrol vapour through the main jet. This mixture passes into the cylinders making the engine run faster.

Some modern cars use a petrol injection systems instead of a carburettor. This injects the fuel into each cylinder under pressure and so provides a better engine performance. Sometimes the system is electronically controlled.

4. Answer the questions:

1) What is the purpose of the carburetor?

2) What does a fuel mixture consist of?

3) How does a fuel mixture vary?

4) In what case is a fuel mixture said to be «rich»?

5) What gives a «weak» mixture?

6) What does a carburetor consist of?

7) What is the purpose of a float chamber?

8) What is the flow of air into the carburetor controlled by?

5. You should say with one word:

1. engine that burns fuel inside its cylinder to produce power

2. device that mixes petrol with air in correct proportion for combustion

3. carburetorless fuel system that injects a programmed amount of fuel into the induction manifold of an internal-combustion engine

4. pipe with tubes connecting the carburettor to the inlet ports

5. combination of petrol and air used to power an engine

6. pivoting metal plate resembling a butterflyˊs wings, that controls the flow of air or fuel mixture within a carburettor

7. small opening that permits a controlled amount of fuel to enter a carburetor

6. Translate the verbs formed by conversion:

speed- to speed, proportion - to proportion , jet -to jet, mist- to mist, reserve -to reserve, vapour- to vapour, use -to use, fuel - to fuel