| The sole responsible component for the motion of | | | | keep the correct air-fuel ratio throughout the |
| a vehicle is the engine. For the engine, to enable | | | | range of speeds and loads of engine. |
| such motion is through combustion, or the burning | | | | The float circuit maintains the fuel in the |
| of the fuel to create pressure, which then creates | | | | carburetor at a certain level even in the harshest |
| for motion. A remarkably tiny amount of fuel is | | | | conditions. It maintains the fuel level. When its |
| needed during each combustion cycle. Mix it with | | | | attached lever forces the needle valve closed, the |
| air, fuel is burnt during combustion process for the | | | | flow of the fuel from the pump is stopped. The |
| engine to create pressure. | | | | needle valve opens and fuel flows into the bowl |
| To achieve the process, the carburetor is installed | | | | again. In this way, the fuel is level to the opening |
| to mix jut the right amount of gasoline with air so | | | | of the main discharge nozzle. The float level must |
| that the engine runs smoothly. If there is not | | | | be set with a high degree of accuracy. If the level |
| enough fuel mixed with air, the engine "runs lean" | | | | is too low, not enough fuel will be supplied to the |
| and either will not run or will potentially damage | | | | system and the engine will stall on turns. If the |
| the engine. Having too much fuel mixed with air | | | | level is too high, too much fuel will flow from the |
| will make the engine "run rich" and will: not run | | | | nozzle. |
| (during floods); run very smoky; run poorly (bogs | | | | The metering rod will tell how much sizes will the |
| down, stall easily); or will even waste fuel. The | | | | carburetor jet opens. The fuel from the float |
| carburetor will makes this mixture at the right | | | | bowl is metered through the jet and the metering |
| amount. | | | | rod within it. The fuel is forced from the jet to |
| Carburetors are still found in small engines and in | | | | the nozzle extending into the venturi. As the |
| older or specialized automobiles such as those | | | | throttle valve is opened, its linkage raises the |
| designed for stock car racing. However, fuel | | | | metering rod from the jet. The rod has several |
| injection first introduced in the late 1950's and first | | | | steps, or tapers, on the lower end. As it is raised |
| successfully commercialized in the early 1970s, | | | | in the jet, it makes the opening of the jet greater |
| have become nearly universal a sit provides | | | | in size. This allows more fuel to flow through the |
| better fuel efficiency and lower emissions. But | | | | jet to the discharge nozzle. |
| nearly all older cars and other small equipment like | | | | When the engine is cold, the choke valves make |
| lawnmowers and chainsaws use carburetors | | | | the necessary fuel mixture adjustments to start |
| because of its simplicity and low cost in | | | | it. The engine won't start properly with a cold |
| comparison with fuel injections. | | | | fuel-air mixture. It will even stall out periodically. |
| Running at idle or when it is cold, the engine is | | | | When "engaged" (closed) it will increase the fuel air |
| supplied by the carburetor with a small amount of | | | | mixture, or otherwise, increased. Placed at the |
| very rich fuel mixture. As the throttle plate is | | | | mouth of the carburetor, the choke is a special |
| closed and air from the air cleaner is limited by | | | | valve that partially blocks off the entering air. |
| the closed choke plate, engine suction is amplified | | | | When the choke plate closes, the vacuum below |
| at idle-circuit nozzle. This vacuum draws a thick | | | | it increases, drawing more fuel from the fuel bowl. |
| spray of gasoline through the nozzle from the full | | | | The rich fuel mixture burns even at lower |
| float bowl, whose fuel line is closed by the | | | | temperatures, allowing the engine to warm up. |
| float-supported needle valve. More fuel is provided | | | | Also added inside the carburetor is the idle circuit |
| when the gas pedal is depressed for acceleration. | | | | that keeps the engine running smoothly and |
| The pedal linkage opens the throttle plate and the | | | | evenly when no power is necessary. Also known |
| choke plate to send air rushing through the barrel. | | | | as the idle jet, it admits fuel on the engine side of |
| The linkage also depresses the accelerator pump, | | | | the throttle valve. Additional air is mixed with the |
| providing added gasoline through the | | | | fuel through the air bleed. This result to an entirely |
| accelerator-circuit nozzle. As air passes through | | | | separates carburetor circuit that functions only |
| the narrow center of the barrel, called the | | | | when the throttle valve is closed. |
| "venturi;" it produces suction that draws spray | | | | Though the parts may function in seemingly |
| from the cruising-circuit nozzle. The float-bowl | | | | complicated ways, these components perform |
| level drops and causes the float to tip and the | | | | each task for the whole carburetor to work |
| needle valve to open the fuel line. | | | | efficiently. As it mixes with the right amount of air |
| When liquid or air passes through the venturi tube, | | | | and fuel, no doubt that the engine will run |
| the speed of flow is increased at the restriction. | | | | smoothly albeit the impending hassle that may |
| Thus, air pressure is lowered, creating an | | | | come along the way. These carburetor parts can |
| "increase in vacuum" or a reduction in ambient | | | | be availed at the nearest auto parts stores |
| pressure. This will enable for the fuel to be drawn | | | | nearby and through online aftermarket stores in |
| into the barrel. This venturi process is used to | | | | cyberspace. |