Carburetor - Revision history

Red marquis: /* Idle circuit */

2008-12-15T02:12:55Z

Idle circuit

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	=== Idle circuit ===		=== Idle circuit ===
	When the throttle valve is closed or nearly closed, the carburetor's ''idle circuit'' is in operation. The closed throttle reduces the airflow through the venturi to a level which cannot overcome the resistance to flow of the fuel, but it also means that a fairly significant [[vacuum]] occurs behind the closed butterfly valve. This [[manifold (automotive engineering)\|manifold]] vacuum is sufficient to pull fuel through small openings placed after the butterfly valve (and in SU and similar sidedraft carburetors to pull the piston and metering rod up).		When the throttle valve is closed or nearly closed, the carburetor's ''idle circuit'' is in operation. The closed throttle reduces the airflow through the venturi to a level which cannot overcome the resistance to flow of the fuel, but it also means that a fairly significant vacuum occurs behind the closed butterfly valve. This [[manifold (automotive engineering)\|manifold]] vacuum is sufficient to pull fuel through small openings placed after the butterfly valve (and in SU and similar sidedraft carburetors to pull the piston and metering rod up).

	Only a fairly small amount of air and fuel can pass through in this manner. Since this small volume of fuel/air mixture can generate so little force to keep the engine turning, keeping it running at idle is more difficult than keeping it running at higher speeds. Since the airflow is too low for the carburetor to respond at all, it cannot compensate for fluctuations;instead, idle airflow is set manually by the technician or mechanic, adjusting a screw which opens the throttle a tiny fraction to allow a minimal amount of air to pass, and another screw which serves as a valve in the idle fuel circuit to adjust the volume of fuel delivered. These adjustments interact with each other, as well as affecting manifold vacuum which affects [[distributor]] spark advance which in turn affects idle speed, so that adjusting the idle to optimum (highest manifold vacuum at the specified engine idle speed) is not a completely trivial operation. While experts often claim the ability to set the idle perfectly by ear, most individuals do a better job using a [[tachometer]] and vacuum gauge. Since the advent of emissions controls on production automobiles, the idle fuel flow is typically set at the factory on the "lean" side of optimal, by restricting fuel flow so that idle speed falls by 100 — 150 rpm from where it was when optimally adjusted, in order to reduce unburned hydrocarbons and carbon monoxide with some slight loss in reliable and smooth idling; the idle fuel adjustment is typically sealed at the factory to prevent tampering, so that adjustment when age and wear cause a large deviation from proper operation requires drilling out a plug over the adjusting screw or some similar modification to gain access.		Only a fairly small amount of air and fuel can pass through in this manner. Since this small volume of fuel/air mixture can generate so little force to keep the engine turning, keeping it running at idle is more difficult than keeping it running at higher speeds. Since the airflow is too low for the carburetor to respond at all, it cannot compensate for fluctuations;instead, idle airflow is set manually by the technician or mechanic, adjusting a screw which opens the throttle a tiny fraction to allow a minimal amount of air to pass, and another screw which serves as a valve in the idle fuel circuit to adjust the volume of fuel delivered. These adjustments interact with each other, as well as affecting manifold vacuum which affects [[distributor]] spark advance which in turn affects idle speed, so that adjusting the idle to optimum (highest manifold vacuum at the specified engine idle speed) is not a completely trivial operation. While experts often claim the ability to set the idle perfectly by ear, most individuals do a better job using a [[tachometer]] and vacuum gauge. Since the advent of emissions controls on production automobiles, the idle fuel flow is typically set at the factory on the "lean" side of optimal, by restricting fuel flow so that idle speed falls by 100 — 150 rpm from where it was when optimally adjusted, in order to reduce unburned hydrocarbons and carbon monoxide with some slight loss in reliable and smooth idling; the idle fuel adjustment is typically sealed at the factory to prevent tampering, so that adjustment when age and wear cause a large deviation from proper operation requires drilling out a plug over the adjusting screw or some similar modification to gain access.

Red marquis at 02:12, 15 December 2008

2008-12-15T02:12:17Z

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	== Multiple carburetor barrels ==		== Multiple carburetor barrels ==
	[[Image:1961 Ferrari 250 TR 61 Spyder Fantuzzi engine.jpg\|right\|thumb\|250px\|[[Ferrari Colombo engine\|Colombo]] Type 125 "Testa Rossa" engine in a 1961 [[Ferrari TR\|Ferrari 250TR Spyder]] with 6 Weber 2-barrel carburetors intaking air through 12 "trumpets" visible on top of the engine, one individually adjustable barrel for each cylinder; the ultimate in tunability.]]

	While low performance carburetors may have only one barrel, most carburetors have more than one venturi, or "barrel", most commonly a two barrel, with 4 barrels being common in higher performance larger displacement engines, to accommodate the higher air flow rate with larger [[engine displacement]]. Multi-barrel carburetors can have non-identical primary and secondary barrel(s) of different sizes and calibrated to deliver different air/fuel mixtures; they can be actuated by the linkage or by engine vacuum in "progressive" fashion, so that the secondary barrels do not begin to open until the primaries are almost completely open. This is a desirable characteristic which maximizes airflow through the primary barrel(s) at most engine speeds, thereby maximizing the pressure "signal" from the venturis, but reduces the restriction in airflow at high speeds by adding cross-sectional area for greater airflow. These advantages may not be important in high-performance applications where part throttle operation is irrelevant, and the primaries and secondaries may all open at once, for simplicity and reliability; also, V configuration engines, with two cylinder banks fed by a single carburetor, may be configured with two identical barrels, each supplying one cylinder bank. Similarly, in the widely seen V8 and 4-barrel carburetor combination, there are often two primary and two secondary barrels.		While low performance carburetors may have only one barrel, most carburetors have more than one venturi, or "barrel", most commonly a two barrel, with 4 barrels being common in higher performance larger displacement engines, to accommodate the higher air flow rate with larger [[engine displacement]]. Multi-barrel carburetors can have non-identical primary and secondary barrel(s) of different sizes and calibrated to deliver different air/fuel mixtures; they can be actuated by the linkage or by engine vacuum in "progressive" fashion, so that the secondary barrels do not begin to open until the primaries are almost completely open. This is a desirable characteristic which maximizes airflow through the primary barrel(s) at most engine speeds, thereby maximizing the pressure "signal" from the venturis, but reduces the restriction in airflow at high speeds by adding cross-sectional area for greater airflow. These advantages may not be important in high-performance applications where part throttle operation is irrelevant, and the primaries and secondaries may all open at once, for simplicity and reliability; also, V configuration engines, with two cylinder banks fed by a single carburetor, may be configured with two identical barrels, each supplying one cylinder bank. Similarly, in the widely seen V8 and 4-barrel carburetor combination, there are often two primary and two secondary barrels.
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	== History and development ==		== History and development ==
	The carburetor was invented by the ~~[[Hungary\|~~Hungarian~~]] [[~~engineer]] [[Donát Bánki]] in 1893. [[Frederick William Lanchester]] of [[Birmingham]], England experimented early on with the wick carburetor in cars. In 1896 Frederick and his brother built the first petrol driven car in England, a single cylinder 5 [[HP\|hp]] (4 kW) internal combustion engine with chain drive. Unhappy with the performance and power, they re-built the engine the next year into a two cylinder horizontally opposed version using his new wick carburetor design. This version completed a 1,000 mile (1600 km) tour in 1900 successfully incorporating the carburetor as an important step forward in automotive engineering.		The carburetor was invented by the Hungarian engineer [[Donát Bánki]] in 1893. [[Frederick William Lanchester]] of Birmingham, England experimented early on with the wick carburetor in cars. In 1896 Frederick and his brother built the first petrol driven car in England, a single cylinder 5 [[HP\|hp]] (4 kW) internal combustion engine with chain drive. Unhappy with the performance and power, they re-built the engine the next year into a two cylinder horizontally opposed version using his new wick carburetor design. This version completed a 1,000 mile (1600 km) tour in 1900 successfully incorporating the carburetor as an important step forward in automotive engineering.

	The word ''carburetor'' comes from the French ''carbure'', meaning '[[carbide]]' [http://www.answers.com/carburet&r=67]. To ''carburete'' means to combine with [[carbon]]. In fuel chemistry, the term has the more specific meaning of increasing the [[carbon]] (and therefore energy) content of a fuel by mixing it with a volatile [[hydrocarbon]].		The word ''carburetor'' comes from the French ''carbure'', meaning '[[carbide]]' [http://www.answers.com/carburet&r=67]. To ''carburete'' means to combine with [[carbon]]. In fuel chemistry, the term has the more specific meaning of increasing the [[carbon]] (and therefore energy) content of a fuel by mixing it with a volatile [[hydrocarbon]].

Red marquis: /* Carburetor adjustment */

2008-12-15T01:30:10Z

Carburetor adjustment

← Older revision		Revision as of 01:30, 15 December 2008
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	See also [[Spark plug#Reading spark plugs\|reading spark plugs]].		See also [[Spark plug#Reading spark plugs\|reading spark plugs]].

	In the early 1980s, many American-market vehicles used special "feedback" carburetors that could change the base mixture in response to signals from an exhaust gas [[Oxygen sensor]]. These were mainly used to save costs (since they worked well enough to meet 1980s emissions requirements and were based on existing carburetor designs), but eventually disappeared as falling hardware prices and tighter emissions standards made [[fuel injection]] a standard item.		In the early 1980s, many American-market vehicles used special "feedback" carburetors that could change the base mixture in response to signals from an exhaust gas Oxygen sensor. These were mainly used to save costs (since they worked well enough to meet 1980s emissions requirements and were based on existing carburetor designs), but eventually disappeared as falling hardware prices and tighter emissions standards made [[fuel injection]] a standard item.

	== History and development ==		== History and development ==

67.172.249.52: /* Carburetor adjustment */

2008-12-14T12:03:56Z

Carburetor adjustment

← Older revision		Revision as of 12:03, 14 December 2008
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	== Carburetor adjustment ==		== Carburetor adjustment ==
	Too much fuel in the fuel-air mixture is referred to as too "rich"; not enough fuel is too "lean". The "mixture" is normally controlled by adjustable screws on an automotive carburetor, or a pilot-operated lever on piston-engined aircraft (since mixture is air density (altitude) dependent). The ([[stoichiometry\|stoichiometric]]) air to [[petrol]] ratio is 14.6:1, meaning that for each weight unit of petrol, 14.6 units of air will be burned. In theory this the most efficient regarding the power/consumption ratio.		Too much fuel in the fuel-air mixture is referred to as too "rich"; not enough fuel is too "lean". The "mixture" is normally controlled by adjustable screws on an automotive carburetor, or a pilot-operated lever on piston-engined aircraft (since mixture is air density (altitude) dependent). The ([[stoichiometry\|stoichiometric]]) air to [[petrol]] ratio is 14.7:1, meaning that for each weight unit of petrol, 14.7 units of air will be burned. In theory this the most efficient regarding the power/consumption ratio.

	But as combustion chambers in use on engines are not able to allow complete combustion of the gasoline with stoichiometric mixture, a mix around 18:1 will give better results regarding fuel economy and pollution, the excess air allowing more complete combustion.		But as combustion chambers in use on engines are not able to allow complete combustion of the gasoline with stoichiometric mixture, a mix around 18:1 will give better results regarding fuel economy and pollution, the excess air allowing more complete combustion.

Red marquis: /* Further reading */

2008-10-29T11:06:53Z

Red marquis at 10:51, 29 October 2008

2008-10-29T10:51:19Z

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	[[image:713px-Strombergcarb.jpg\|thumb\|right\|300px\|Stromberg side-draft carburetor]]		[[image:713px-Strombergcarb.jpg\|thumb\|right\|300px\|Stromberg side-draft carburetor]]
	The '''carburetor''', '''carburettor''', or '''carburetter''' (see [[spelling differences]]), also called ''carb'' (in North America) or ''carbie'' (chiefly in Australia) for short, is a device that mixes ~~[[Earth's atmosphere\|~~air]] and [[fuel]] for an [[internal-combustion engine]]. It was invented by Hungarian scientists [[Donát Bánki]] and [[János Csonka]] in 1893. Carburetors are still found in small engines and in older or specialized [[automobile]]s such as those designed for [[stock car racing]]. However, [[fuel injection]], first introduced in the late 1950s and first successfully commercialized in the early 1970s, is now the preferred method of automotive fuel delivery. The majority of [[motorcycles]] still are carburated due to lower weight and cost, but [[as of 2005]] many new models are now being introduced with [[fuel injection]].		The '''carburetor''', '''carburettor''', or '''carburetter''' (see spelling differences), also called ''carb'' (in North America) or ''carbie'' (chiefly in Australia) for short, is a device that mixes air and [[fuel]] for an [[internal-combustion engine]]. It was invented by Hungarian scientists [[Donát Bánki]] and [[János Csonka]] in 1893. Carburetors are still found in small engines and in older or specialized [[automobile]]s such as those designed for [[stock car racing]]. However, [[fuel injection]], first introduced in the late 1950s and first successfully commercialized in the early 1970s, is now the preferred method of automotive fuel delivery. The majority of motorcycles still are carburated due to lower weight and cost, but as of 2005 many new models are now being introduced with [[fuel injection]].

	Most '''carbureted''' (as opposed to [[fuel-injected]]) engines have a single carburetor, though some engines use multiple carburetors. Older engines used updraft carburetors, where the air enters from below the carburetor and exits through the top. This had the advantage of never "flooding" the engine, as any liquid fuel droplets would fall out of the carburetor instead of into the [[intake manifold]]; it also lent itself to use of an [[motor oil\|oil]] bath [[air cleaner]], where a pool of oil below a mesh element below the carburetor is sucked up into the mesh and the air is drawn through the oil covered mesh; this was an effective system in a time when paper [[air ~~filter]]s~~ did not exist. Beginning in the late 1930s, downdraft carburetors were the most popular type for automotive use in the [[United States]]. In Europe, the sidedraft carburettors replaced downdraft as [[hood (vehicle)\|underbonnet/underhood]] space decreased and the use of the [[SU carburetor\|SU]]-type carburetor (and similar units from other manufacturers) increased. Small propeller-driven flat aircraft engines still use the updraft carburetor design.		Most '''carbureted''' (as opposed to [[fuel-injected]]) engines have a single carburetor, though some engines use multiple carburetors. Older engines used updraft carburetors, where the air enters from below the carburetor and exits through the top. This had the advantage of never "flooding" the engine, as any liquid fuel droplets would fall out of the carburetor instead of into the [[intake manifold]]; it also lent itself to use of an [[motor oil\|oil]] bath air cleaner, where a pool of oil below a mesh element below the carburetor is sucked up into the mesh and the air is drawn through the oil covered mesh; this was an effective system in a time when paper air filters did not exist. Beginning in the late 1930s, downdraft carburetors were the most popular type for automotive use in the United States. In Europe, the sidedraft carburettors replaced downdraft as [[hood (vehicle)\|underbonnet/underhood]] space decreased and the use of the [[SU carburetor\|SU]]-type carburetor (and similar units from other manufacturers) increased. Small propeller-driven flat aircraft engines still use the updraft carburetor design.

	The carburetor works on [[Bernoulli's principle]]: the fact that moving air has lower pressure than still air, and that the faster the movement of the air, the lower the pressure. The [[throttle]] or accelerator does not control the flow of liquid fuel. Instead, it controls the amount of air that flows through the carburetor. Faster flows of air and more air entering the carburetor draws more fuel into the carburetor due to the partial [[vacuum]] that is created.		The carburetor works on Bernoulli's principle: the fact that moving air has lower pressure than still air, and that the faster the movement of the air, the lower the pressure. The [[throttle]] or accelerator does not control the flow of liquid fuel. Instead, it controls the amount of air that flows through the carburetor. Faster flows of air and more air entering the carburetor draws more fuel into the carburetor due to the partial vacuum that is created.

	== Operation ==		== Operation ==

Red marquis: /* Catalytic carburetors */

2008-10-29T10:49:41Z

Catalytic carburetors

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	== Catalytic carburetors ==		== Catalytic carburetors ==
	There are persistent rumours that appear to extend into the realm of [[urban legend]] or even into conspiracy theory of extremely efficient carburetors. However, there may be some basis for these rumors or claims.		There are persistent rumours that appear to extend into the realm of urban legend or even into conspiracy theory of extremely efficient carburetors. However, there may be some basis for these rumors or claims.

	A catalytic carburetor mixes fuel fumes with water and air in the presence of heated catalysts such as nickel or platinum. The fuel would break down into methane, alcohols, and other lighter-weight fuels. The original catalytic carburetor was introduced to permit farmers to run tractors from modified and enriched kerosene.		A catalytic carburetor mixes fuel fumes with water and air in the presence of heated catalysts such as nickel or platinum. The fuel would break down into methane, alcohols, and other lighter-weight fuels. The original catalytic carburetor was introduced to permit farmers to run tractors from modified and enriched kerosene.
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	However, it is known that less than two years after commercial introduction of the first catalytic carburetor, in 1932, tetraethyl lead was introduced as an additive to raise gasoline's resistance to [[Engine knock\|spontaneous combustion]], thereby permitting the use of higher compression ratios. Also in that time, the price differential between a thermal calorie of gasoline and kerosene was ended. Tetraethyl lead had the effect of poisoning catalytic carburetors. Many modern gasolines appear to have additives for "cleaning" which perform the same effect by producing varnishes or gums in the presence of water, which of course, is not a recommended use.		However, it is known that less than two years after commercial introduction of the first catalytic carburetor, in 1932, tetraethyl lead was introduced as an additive to raise gasoline's resistance to [[Engine knock\|spontaneous combustion]], thereby permitting the use of higher compression ratios. Also in that time, the price differential between a thermal calorie of gasoline and kerosene was ended. Tetraethyl lead had the effect of poisoning catalytic carburetors. Many modern gasolines appear to have additives for "cleaning" which perform the same effect by producing varnishes or gums in the presence of water, which of course, is not a recommended use.

	Gasoline/petrol is an impure mixture of linear [[heptane]] and [[octane]] and other miscellaneous light alkanes. Commercial gasolines usually contain additives to clean engines, artificially lower evaporation points, and (conjecturally) poison catalytic carburetors (an effect that is certainly real, but might be accidental).		Gasoline/petrol is an impure mixture of linear heptane and octane and other miscellaneous light alkanes. Commercial gasolines usually contain additives to clean engines, artificially lower evaporation points, and (conjecturally) poison catalytic carburetors (an effect that is certainly real, but might be accidental).

	Famed [[NASCAR]] mechanic Smokey Yunick spent many years working on a high fuel economy "vapor carburetor". The detailed operation is not widely disseminated, but the general principle is to heat the fuel with waste engine heat to enhance vaporization and improve the fuel's combustion characteristics. This was reasonably effective compared to normal carburetors of the time, but had implementation difficulties. During the years he was developing it, the average production engine moved from centrally located carburetors to electronic [[fuel injection]], wherein the fuel is delivered right to the intake port. This dramatically reduces fuel condensation and puddling in the [[Manifold (automotive engineering)\|intake manifold]] and runners, making Smokey's design a solution to a problem which no longer existed so it was never commercially developed.		Famed [[NASCAR]] mechanic Smokey Yunick spent many years working on a high fuel economy "vapor carburetor". The detailed operation is not widely disseminated, but the general principle is to heat the fuel with waste engine heat to enhance vaporization and improve the fuel's combustion characteristics. This was reasonably effective compared to normal carburetors of the time, but had implementation difficulties. During the years he was developing it, the average production engine moved from centrally located carburetors to electronic [[fuel injection]], wherein the fuel is delivered right to the intake port. This dramatically reduces fuel condensation and puddling in the [[Manifold (automotive engineering)\|intake manifold]] and runners, making Smokey's design a solution to a problem which no longer existed so it was never commercially developed.



	==Further reading==		==Further reading==

Red marquis: /* Further reading */

2008-10-29T10:49:05Z

Carguy at 20:00, 27 June 2006

2006-06-27T20:00:44Z

← Older revision		Revision as of 20:00, 27 June 2006
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	[[image:713px-Strombergcarb\|thumb\|right\|300px\|Stromberg side-draft carburetor]]		[[image:713px-Strombergcarb.jpg\|thumb\|right\|300px\|Stromberg side-draft carburetor]]
	The '''carburetor''', '''carburettor''', or '''carburetter''' (see [[spelling differences]]), also called ''carb'' (in North America) or ''carbie'' (chiefly in Australia) for short, is a device that mixes [[Earth's atmosphere\|air]] and [[fuel]] for an [[internal-combustion engine]]. It was invented by Hungarian scientists [[Donát Bánki]] and [[János Csonka]] in 1893. Carburetors are still found in small engines and in older or specialized [[automobile]]s such as those designed for [[stock car racing]]. However, [[fuel injection]], first introduced in the late 1950s and first successfully commercialized in the early 1970s, is now the preferred method of automotive fuel delivery. The majority of [[motorcycles]] still are carburated due to lower weight and cost, but [[as of 2005]] many new models are now being introduced with [[fuel injection]].		The '''carburetor''', '''carburettor''', or '''carburetter''' (see [[spelling differences]]), also called ''carb'' (in North America) or ''carbie'' (chiefly in Australia) for short, is a device that mixes [[Earth's atmosphere\|air]] and [[fuel]] for an [[internal-combustion engine]]. It was invented by Hungarian scientists [[Donát Bánki]] and [[János Csonka]] in 1893. Carburetors are still found in small engines and in older or specialized [[automobile]]s such as those designed for [[stock car racing]]. However, [[fuel injection]], first introduced in the late 1950s and first successfully commercialized in the early 1970s, is now the preferred method of automotive fuel delivery. The majority of [[motorcycles]] still are carburated due to lower weight and cost, but [[as of 2005]] many new models are now being introduced with [[fuel injection]].

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	To ensure a ready supply of fuel, the carburetor has a "float chamber" (or "bowl") that contains a quantity of fuel at near-atmospheric pressure, ready for use. This reservoir is constantly replenished with fuel supplied by a [[fuel pump]]. The correct fuel level in the bowl is maintained by means of a float controlling an inlet valve, in a manner very similar to that employed in toilet tanks. As fuel is used up, the float drops, opening the inlet valve and admitting fuel. As the fuel level rises, the float rises and closes the inlet valve. The level of fuel maintained in the float bowl can usually be adjusted, whether by a setscrew or by something crude such as bending the arm to which the float is connected. This is usually a critical adjustment, and the proper adjustment is indicated by lines scribed into a window on the float bowl, or a measurement of how far the float hangs below the top of the carburetor when disassembled, or similar. Floats can be made of different materials, such as sheet brass soldered into a hollow shape, or of plastic; hollow floats can spring small leaks and plastic floats can eventually become porous and lose their flotation; in either case the float will fail to float, fuel level will be too high, and the engine will not run well unless the float is replaced. The valve itself becomes worn on its sides by its motion in its "seat" and will eventually try to close at an angle, and thus fails to shut off the fuel completely; again, this will cause excessive fuel flow and poor engine operation. Conversely, as the fuel evaporates from the float bowl, it leaves sediment, residue, and varnishes behind, which clog the passages and can interfere with the float operation. This is particularly a problem in automobiles operated for only part of the year and left to stand with full float chambers for months at a time; commercial fuel stabilizer additives are available that reduce this problem.		To ensure a ready supply of fuel, the carburetor has a "float chamber" (or "bowl") that contains a quantity of fuel at near-atmospheric pressure, ready for use. This reservoir is constantly replenished with fuel supplied by a [[fuel pump]]. The correct fuel level in the bowl is maintained by means of a float controlling an inlet valve, in a manner very similar to that employed in toilet tanks. As fuel is used up, the float drops, opening the inlet valve and admitting fuel. As the fuel level rises, the float rises and closes the inlet valve. The level of fuel maintained in the float bowl can usually be adjusted, whether by a setscrew or by something crude such as bending the arm to which the float is connected. This is usually a critical adjustment, and the proper adjustment is indicated by lines scribed into a window on the float bowl, or a measurement of how far the float hangs below the top of the carburetor when disassembled, or similar. Floats can be made of different materials, such as sheet brass soldered into a hollow shape, or of plastic; hollow floats can spring small leaks and plastic floats can eventually become porous and lose their flotation; in either case the float will fail to float, fuel level will be too high, and the engine will not run well unless the float is replaced. The valve itself becomes worn on its sides by its motion in its "seat" and will eventually try to close at an angle, and thus fails to shut off the fuel completely; again, this will cause excessive fuel flow and poor engine operation. Conversely, as the fuel evaporates from the float bowl, it leaves sediment, residue, and varnishes behind, which clog the passages and can interfere with the float operation. This is particularly a problem in automobiles operated for only part of the year and left to stand with full float chambers for months at a time; commercial fuel stabilizer additives are available that reduce this problem.

	Usually, special vent tubes allow air to escape from the chamber as it fills or enter as it empties, maintaining atmospheric pressure within the float chamber; these usually extend into the carburetor throat. Placement of these vent tubes can be somewhat critical to prevent fuel from sloshing out of them into the carburetor, and sometimes they are modified with longer tubing. Note that this leaves the fuel at atmospheric pressure, and therefore it cannot travel into a throat which has been pressurized by a [[Supercharged Engine\|supercharger]] mounted upstream; in such cases, the entire carburetor must be contained in an airtight pressurized box to operate. This is not necessary in installations where the carburetor is mounted upstream of the supercharger, which is for this reason the more frequent system. However, this results in the supercharger being filled with compressed fuel/air mixture, with a strong tendency to explode should the engine backfire; this type of explosion is frequently seen in drag races, which for safety reasons now incorporate pressure releasing blow-off plates on the intake manifold, breakaway bolts holding the supercharger to the manifold, and shrapnel-catching ballistic nylon blankets surrounding the superchargers.		Usually, special vent tubes allow air to escape from the chamber as it fills or enter as it empties, maintaining atmospheric pressure within the float chamber; these usually extend into the carburetor throat. Placement of these vent tubes can be somewhat critical to prevent fuel from sloshing out of them into the carburetor, and sometimes they are modified with longer tubing. Note that this leaves the fuel at atmospheric pressure, and therefore it cannot travel into a throat which has been pressurized by a [[Supercharged Engine\|supercharger]] mounted upstream; in such cases, the entire carburetor must be contained in an airtight pressurized box to operate. This is not necessary in installations where the carburetor is mounted upstream of the [[Supercharged Engine\|supercharger]], which is for this reason the more frequent system. However, this results in the [[Supercharged Engine\|supercharger]] being filled with compressed fuel/air mixture, with a strong tendency to explode should the engine backfire; this type of explosion is frequently seen in drag races, which for safety reasons now incorporate pressure releasing blow-off plates on the intake manifold, breakaway bolts holding the [[Supercharged Engine\|supercharger]] to the manifold, and shrapnel-catching ballistic nylon blankets surrounding the [[Supercharged Engine\|superchargers]].

	If the engine must be operated in any orientation (for example a chain saw), a float chamber cannot work. Instead, a diaphragm chamber is used. A flexible diaphragm forms one side of the fuel chamber and is arranged so that as fuel is drawn out into the engine the diaphragm is forced inward by ambient air pressure. The diaphragm is connected to the needle valve and as it moves inward it opens the needle valve to admit more fuel, thus replenishing the fuel as it is consumed. As fuel is replenished the diaphragm moves out due to fuel pressure and a small spring, closing the needle valve. A balanced state is reached which creates a steady fuel reservoir level, which remains constant in any orientation.		If the engine must be operated in any orientation (for example a chain saw), a float chamber cannot work. Instead, a diaphragm chamber is used. A flexible diaphragm forms one side of the fuel chamber and is arranged so that as fuel is drawn out into the engine the diaphragm is forced inward by ambient air pressure. The diaphragm is connected to the needle valve and as it moves inward it opens the needle valve to admit more fuel, thus replenishing the fuel as it is consumed. As fuel is replenished the diaphragm moves out due to fuel pressure and a small spring, closing the needle valve. A balanced state is reached which creates a steady fuel reservoir level, which remains constant in any orientation.
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	== History and development ==		== History and development ==
	The carburetor was invented by the [[Hungary\|Hungarian]] [[engineer]] [[Donát Bánki]] in 1893. [[Frederick William Lanchester]] of [[Birmingham]], England experimented early on with the wick carburetor in cars. In 1896 Frederick and his brother built the first petrol driven car in England, a single cylinder 5 hp (4 kW) internal combustion engine with chain drive. Unhappy with the performance and power, they re-built the engine the next year into a two cylinder horizontally opposed version using his new wick carburetor design. This version completed a 1,000 mile (1600 km) tour in 1900 successfully incorporating the carburetor as an important step forward in automotive engineering.		The carburetor was invented by the [[Hungary\|Hungarian]] [[engineer]] [[Donát Bánki]] in 1893. [[Frederick William Lanchester]] of [[Birmingham]], England experimented early on with the wick carburetor in cars. In 1896 Frederick and his brother built the first petrol driven car in England, a single cylinder 5 [[HP\|hp]] (4 kW) internal combustion engine with chain drive. Unhappy with the performance and power, they re-built the engine the next year into a two cylinder horizontally opposed version using his new wick carburetor design. This version completed a 1,000 mile (1600 km) tour in 1900 successfully incorporating the carburetor as an important step forward in automotive engineering.

	The word ''carburetor'' comes from the French ''carbure'', meaning '[[carbide]]' [http://www.answers.com/carburet&r=67]. To ''carburete'' means to combine with [[carbon]]. In fuel chemistry, the term has the more specific meaning of increasing the [[carbon]] (and therefore energy) content of a fuel by mixing it with a volatile [[hydrocarbon]].		The word ''carburetor'' comes from the French ''carbure'', meaning '[[carbide]]' [http://www.answers.com/carburet&r=67]. To ''carburete'' means to combine with [[carbon]]. In fuel chemistry, the term has the more specific meaning of increasing the [[carbon]] (and therefore energy) content of a fuel by mixing it with a volatile [[hydrocarbon]].

Carguy at 20:00, 27 June 2006

2006-06-27T20:00:25Z

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	[[image:~~strombergcarb.jpg~~\|thumb\|right\|300px\|Stromberg side-draft carburetor]]		[[image:713px-Strombergcarb\|thumb\|right\|300px\|Stromberg side-draft carburetor]]
	The '''carburetor''', '''carburettor''', or '''carburetter''' (see [[spelling differences]]), also called ''carb'' (in North America) or ''carbie'' (chiefly in Australia) for short, is a device that mixes [[Earth's atmosphere\|air]] and [[fuel]] for an [[internal-combustion engine]]. It was invented by Hungarian scientists [[Donát Bánki]] and [[János Csonka]] in 1893. Carburetors are still found in small engines and in older or specialized [[automobile]]s such as those designed for [[stock car racing]]. However, [[fuel injection]], first introduced in the late 1950s and first successfully commercialized in the early 1970s, is now the preferred method of automotive fuel delivery. The majority of [[motorcycles]] still are carburated due to lower weight and cost, but [[as of 2005]] many new models are now being introduced with [[fuel injection]].		The '''carburetor''', '''carburettor''', or '''carburetter''' (see [[spelling differences]]), also called ''carb'' (in North America) or ''carbie'' (chiefly in Australia) for short, is a device that mixes [[Earth's atmosphere\|air]] and [[fuel]] for an [[internal-combustion engine]]. It was invented by Hungarian scientists [[Donát Bánki]] and [[János Csonka]] in 1893. Carburetors are still found in small engines and in older or specialized [[automobile]]s such as those designed for [[stock car racing]]. However, [[fuel injection]], first introduced in the late 1950s and first successfully commercialized in the early 1970s, is now the preferred method of automotive fuel delivery. The majority of [[motorcycles]] still are carburated due to lower weight and cost, but [[as of 2005]] many new models are now being introduced with [[fuel injection]].

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	[[Category:~~Engines~~]]		[[Category:Engine technology]]
	[[Category:Auto parts]]		[[Category:Auto parts]]

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	[[Category:~~Engine fuel system technology~~]]		[[Category:Engines]]
	[[Category:Auto parts]]		[[Category:Auto parts]]