US3759493A

US3759493A - Fuel feed system

Info

Publication number: US3759493A
Application number: US00273377A
Authority: US
Inventors: C Blanchard; R Turner; Bois C Du
Original assignee: Outboard Marine Corp
Current assignee: Outboard Marine Corp
Priority date: 1972-07-20
Filing date: 1972-07-20
Publication date: 1973-09-18
Anticipated expiration: 1990-09-18
Also published as: JPS4945229A; CA993290A

Abstract

Disclosed herein is a carburetor comprising an air induction housing adapted to be connected to the crankcase of an engine and including a pair of air induction passages, a separate high speed fuel nozzle communicating with each of the induction passages and with at least one of the high speed nozzles communicating with a high speed fuel inlet port at the exterior surface of the air induction housing, a low speed fuel nozzle communicating with one of the induction passages and with a low speed fuel inlet port at the exterior surface of the air induction housing, and a fuel feed housing adapted to be mounted on the air induction housing in overlying relation to the high and low speed inlet ports and including a first diaphragm controlled, fuel flow regulating valve communicating with the high speed inlet port in the air induction housing and adapted to be connected to a source of fuel, and a second diaphragm controlled, fuel flow regulating valve communicating with the low speed port in the air induction housing and adapted to be connected to a source of fuel.

Description

[ FUEL FEED SYSTEM [75] Inventors: Clarence E. Blanchard, Kenosha,

Wis.; Robert K. Turner, Waukegan; Chester DuBois, Zion, both of ill.

[73] Assignee: Outboard Marine Corporation,

' Waukegan, Ill.

[22] Filed: July 20, 1972 [21] App]. No.: 273,377

[52] US. 261/23 A, 26l/69 A, 26l/DIG. 68,

[451 Sept. 18, i973 Primary Examiner--Tim R. Miles Attorney-Robert E. Clemency et al.

[57] ABSTRACT Disclosed herein is a carburetor comprising an air induction housing adapted to be connected to the crankcase of an engine and including a pair of air induction passages, a separate high speed fuel nozzle communicating with each of the induction passages and with at least one of the high speed nozzles communicating with a high speed fuel inlet port at the exterior surface of the air induction housing, a low speed fuel nozzle commu-' nicating with one of the induction passages and with a low speed fuel inlet port at the exterior surface of the air induction housing, and a fuel feed housing adapted to be mounted on the air induction housing in overlying relation to the high and low speed inlet ports and including a first diaphragm controlled, fuel flow regulating valve communicating with the high speed inlet port in the air induction housing and adapted to be connected to a source of fuel, and a second diaphragm controlled, fuel flow regulating valve communicating with the low speed port in the air induction housing and adapted to be connected to a source of fuel.

12 Claims, 7 Drawing Figures [51] Int. Cl. F02m 9/06 [58] Field of Search 26l/DlG. 68, 69 A,

261/23 A, 41 D, 35, 67; 123/73 R, 59 B [56] References Cited UNITED STATES PATENTS 2,216,422 l0/l940 Schimanek 26l/DIG. 68 2,345,168 3/1944 Wirth et a1 26l/DlG. 68

3,085,791 4/1963 Phillips 261/DIG. 68 3,269,374 8/1966 Conover 123/59 B 3,272,485 9/1966 Newman 261/DIG. 68 3,377,024 4/1268 Nutten et al..., 26l/DIG. 68 3,453,994 7/1969 Nutten et al 261/DIG. 68

t rust. Fess srsrIsM BACKGROUND OF THE INVENTION The invention relates generally to arrangements for feeding fuel to internal combustion engines and particularly to carburetor arrangements for high speed racing engines.

In past carburetor arrangements, diaphragm controlled regulating valves have been in common use. Typically, a single regulating valve controlled fuel flow to both high speed and low speed nozzles which, in turn, communicated with a single air induction passage. In addition, in prior typical carburetor constructions, the fuel flow regulating arrangement was embodied in an integral portion of the carburetor body or housing and was not readily separable therefrom.

SUMMARY OF THE INVENTION The invention provides a carburetor arrangement comprising separate fuel delivering systems respectively including separate diaphragm controlled, regu' lating valves for controlling fuel flow to each of a high speed nozzle and a low speed nozzle.

The invention also provides a carburetor arrangement including an air induction housing which is adapted to be mounted to the crankcase of a twostroke engine and which includes a plurality of airinduction passages each including a high speed nozzle. At least some of the air induction passages also include a low speed nozzle. Also included are high and low speed fuel inlet ports located on the outer surface of the air induction housing and respectively communicating with the high and low speed nozzles.

Further in accordance with the invention, there is provided a separable fuel feed housing which is detachably mountable on the air induction housing and which includes separate high and low speed outlet ports located so as to mate with the high and low speed inlet ports in the air induction housing when the fuel feed housing is mounted on the air induction housing.

Still further in accordance with the invention, the fuel feed housing includes two separate high and low speed fuel delivering systems each including a diaphragm controlled, fuel regulating valve of the demand type, which valves communicate with a fuel source and which respectively communicate with the high and low speed outlet ports in the fuel feed housing. Each of the high and low speed fuel delivery systems also includes a removable orifice element or other means for additionally regulating fuelflow.

Still further in accordance with one aspect of the invention, the illustrated carburetor arrangement is adapted for use with a four-cylinder two-stroke engine including four separate crankcase chambers. The carburetor arrangement comprises an air induction housing including four nested carburetor units each communicating with a separate one of the crankcase chamhers through a reed valve box and each including two air induction passages which are preferably circular in cross section. Each of the air induction passages in each carburetor unit includes a high speed nozzle and one of the barrels or air induction passages in each carburetor unit includes a low speed nozzle. Preferably all eight barrels or air induction passages are approximately of the same construction and include commonly operated throttle valves.

Also in the preferred embodiment of the invention, each carburetor unit has associated therewith an individual fuel feed housing which is detachably mounted on the air induction housing and which includes separate high and low speed fuel delivery systems each including a fuel flow regulating valve and provision for selective insertion of orifice elements which can include orifices of various sizes so as to tailor the high and low speed fuel delivery systems of each carburetor unit to the associated engine cylinder with the view in mindof optimizing horsepower delivery from each cylinder.

One of the principal objects of the invention is the provision of a carburetor arrangement designed to afford optimum racing performance.

Another of the principal objects of the invention is the provision of a carburetor arrangement affording separate fuel delivery systems for high and low speed nozzles.

Another of the principal objects of the invention is the provision of a multi-barrel carburetor including an air induction housing including a plurality of meshed barrels forming a plurality of carburetor units, together with separate fuel feed means detachably mounted on the air induction housing for each carburetor unit. Each such separate fuel feed means also includes separate high and low speed fuel delivery systems.

Another of the principal objects of the invention is the provision of separately controlled fuel feed housings which are adapted to be mounted on an air induction housing including separate high and low speed nozzles and which include separate high and low speed fuel delivery systems.

Other objects and advantages of the invention will become known by reference to the description, claims, and drawings.

DRAWINGS FIG. l is a fragmentary side elevational view of a carburetor arrangement embodying various of the features of the invention.

FIG. 2 is an enlarged fragmentary and partially schematic view taken generally along line 2-2 of FIG. 1.

FIG. 3 is an end view of the carburetor shown in FIG. i, which view is taken generally along line. 3-3 of FIG. 1. t

, FIG. 4 is a fragmentary view taken along line 4-4 of FIG. 11.

FIG. 5 is an enlarged sectional view taken along line 5-5 of FIG. 3 and showing, in the upper half, a portion of one carburetor unit and, in the lower half, a portion of a second carburetor unit.

FIG. 6 is an enlarged sectional view taken 6-6 of EEG. d.

Fit]. 7 is an enlarged sectional 7-7 of FIG. 5.

Before explaining the invention in detail,"it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts set forth in the following general description or illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

along line view taken along line GENERAL DESCRIPTION Shown fragmentarily in the drawings is an internal combustion engine 11 including a carburetor arrangement 13 which embodies various features of the invention. While carburetor arrangements in accordance with the invention can be employed with engines of various types and can be constructed differently from the specifically illustrated embodiment, the illustrated engine 11 comprises a four-cylinder, two-stroke engine of the type generally disclosed in U.S. Conover Pat. No. 3,269,374, issued Aug. 30, 1966, which is incorporated herein by reference and except that, as will be explained, the reed box-crankcase arrangement in the disclosed construction does not include an array of four aligned reed valve assemblies as shown at 47 in US. Pat. No. 3,269,374. In the illustrated construction, the cylinders(not specifically shown) extend from a crankcase 15 which is sub-divided so as to provide separate crankcase chambers respectively associated with each of the cylinders. In addition, there is mounted to the engine crankcase 15, a reed box 19 including four reed box assemblies or units 21, each associated with a separate one of the crankcase chambers and each including a conventional reed valve 23. Because of the general configuration of the crankcase, each reed box unit 21 is generally of rectangular configuration and the reed box units 21 are grouped in laterally adjacent pairs, as shown in FIG. 4.

In accordance with the invention, the carburetor arrangement 13 is mounted on the reed box 19 and includes an air induction housing 25 and a plurality of fuel-feed housings 27.

More particularly, the air induction housing 25 includes (See FIG. 2) two banks 29 of four air induction tubes, passages or barrels 31 with the air induction tubes 31 in one of the banks 29 being generally in nested and closely adjacent relation to the air induction tubes 31 in the other of the banks 29. Each air induction tube 31 is generally of identical construction, including a circular cross section, and constitutes an air induction passage including (See FIG. an outlet 33 communicating with the associated reed box unit 21 and with an inlet 35 communicating with the atmosphere. lntermediate the inlet 35 and outlet 33 thereof, each barrel or air induction tube 31 can be provided with a venturi section 37. In addition, each barrel or air induction tube 31 has pivotally mounted therein a throttle valve 39. Suitable means are provided for simultaneously operating the throttle valves. One such means including levers 40 which are connected to throttle valve shafts 42 and to each other through an adjustable connecting link 44 is'shown'in FIG. 2.

The two adjacent barrels or air induction tubes 31 at the end of each of the banks 29 constitutes a carburetor unit 41, whereby there are provided four carburetor units 41 which separately and respectively communicate with the four reed box units 21 and which, in further accordance with the preferred embodiment of the invention, each include two barrels or air induction tubes 31 of circular cross section. However, a single barrel with an oblong cross section is within the scope of the invention.

Each of the barrels or air induction tubes 31 in each carburetor unit 41 includes (See FIGS. 5 and 7) a main or high speed nozzle 43 comprising a tube which projects into the barrel or air induction tube 31 upstream from the throttle valve 39 and includes an outlet preferably located in a plane parallel to the axis of the fuel induction passage 31. Each of the high speed nozzles 43 communicates with a respective high speed inlet port 45 at the outer surface of the air induction housing 25. Thus, in the illustrated construction there are two high speed inlet ports 45 for each carburetor unit 41. However, it is within the scope of the invention to provide one high speed inlet port 45 in the air induction housing 25 for each carburetor unit 41 and to provide internal ducting from such a high speed inlet port 45 to as many high speed nozzles 43 as are provided in the carburetor unit 41.

One of the barrels or air induction tubes 31 in each carburetor unit 41 also includes a secondary or low speed nozzle 47 comprising a series of openings 49 which are spaced axially of the barrel or air induction tube 31, which include at least one of such openings 49 on each side of the location of the throttle valve 39 when in closed position, and which communicates with a well 51 which is open to the outer surface of the air induction housing-25 and which can also be regarded as a low speed inlet port.

The area on the outer surface of the air induction housing 25 in the vicinity of the high speed inlet ports 45 and the low speed well 51 is generally planar or flat so as to facilitate sealing against loss of fuel when the associated fuel feed housing 27 is mounted on the air induction housing.

Each of the carburetor units 41 has associated therewith one of the before mentioned plurality of fuel feed housings 27 which are all generally of identical construction and which are adapted to be removably mounted on the air induction housing 25 so as to supply fuel to the high speed inlet port 45 and to the low speed well 51 of the air induction housing 25. Also in accordance with the invention, each fuel feed housing 27 is preferably constructed (See FIGS. 5, 6, and 7) with two mating members, i.e., a housing member 55 and a plate member 57, and so as to include (See FIG. 7) a high speed fuel delivery system 59 and (See FIG. 6) a separate low speed fuel delivery system 61. Each of the high speed and low speed

fuel delivery systems

59 and 61 includes respective fuel feed regulating means 63 and 65 each comprising respective diaphragm operated fuel

flow regulating valves

67 and 69 and

respective metering orifices

71 and 73.

The high speed fuel flow regulating valve 67 includes a valve member 81 which is located in a fuel reservoir or chamber 83 formed by 'a recess or cavity 85 in the housing member 55, and which extends from one end of a centrally pivoted lever 87 for movement relative to a valve seat 89 formed at the end of a fuel inlet duct 91 provided in the housing member 55 in communication with the high speed fuel chamber 83 and adapted for communication with a source of fuel.

The high speed fuel chamber 83 is completed by a diaphragm 93 which extends between the housing member 55 and the plate member 57 and which is engaged by the other end of the lever 87 in response to the action of a spring 95 which also serves to urge the valve member 31 against the valve seat 89 ,to prevent inflow of fuel from the fuel inlet duct 91.

The plate member 57 is also formed with a cavity or recess 97 which is located in opposing relation to the high speed fuel chamber 83 on the other side of the diaphragm 93 and which communicates with the atmosphere through a vent 9h.

The high speed fuel chamber 33 also communicates with an outlet duct 99 which 'is formed in the housing member 55 and which, in turn, communicates with a threaded bore, duct, or conduit lltlll which is formed in the housing member 35 and which receives a threaded orifice element 103 including the high speed metering orifice 71l. At its outer end, the threaded bore 1011 is closed by a threaded plug m3 and, at its inner end, communicates at the interface between the housing member 55 and the plate member 57, with a bore or duct 107 in the plate member 57 which, in turn, terminates in a high speed outlet port M33 in the outer surface of the plate member 57 in position to communicate, when the fuel feed housing 27 is mounted on the air induction housing 25, with one of the high speed inlet ports 45 of the air induction housing 25.

The duct 107 also communicates with a transverse conduit or duct 111 which is formed in the plate member 57, which is plugged at its outer end, and which, in turn, communicates with a duct 113 terminating at the exterior of the platemernber 57 in another high speed outlet port 109 located in position, when the fuel feed housing 27 is mounted on the air induction housing 25, to communicate with the other of the high speed inlet ports 45 of the air induction housing 25. As already indicated, the fuel feed housing 27 can include only one high speed outlet port if the air induction housing 25 is formed to include an appropriate conduit system communicating with the high speed nozzles 13.

Varying orifices 71 of different sizes can be selectively employed in the high speed fueldelivery system 59 simply by unthreading the plug W3 and substituting a different orifice element M13 with a different size orifice 71. If desired, an adjustable needle valve (not shown) could be employed in lieu of the illustrated orifice element.

The low speed fuel flow regulating valve 63 is is constructed generally in the same manner as the high speed fuel flow regulating valve 67 and includes a valve memher 121 extending from a pivoted lever 123 located in a fuel chamber or reservoir 325 formed by a recess 1127 in the housing member 55 on one side of the diaphragm 93. Formed on the other side of the diaphragm 93 in the plate member 57 is a cavity or recess 1129 which communicates with the atmosphere. A spring 13d serves to engage the lever 123 against the diaphragm 93 and to urge the valve member 1211 toward an inlet valve seat 131.

As with respect to the fuel chamber 83 associated with the high speed fuel flow regulating valve 67, the fuel chamber 125 associated with the low speed fuel flow regulating valve 69 communicates with a fuel inlet duct 132 and with a threaded bore or duct 1133 formed in the housing member 55 and having located therein a threaded orifice element 135 including the low speed orifice 73. At its outer end, the threaded bore 133 is closed by a threaded plug 137 and, at its inner end, communicates, at the interface between the housing member 55 and plate member 57, with a bore or duct 139 which extends inthe plate member 57 and tenninates at the exterior thereof with a low speed outlet port 141 in position to communicate, when the fuel feed housing 27 is mounted on the air induction housing 25, with the low speed well 31 in the air induction housing 25.

While the diaphragm operated, fuel flow regulating valves 67 and d9 of both the high speed fuel delivery system 33 and the low speed fuel delivery system 61 are generally of identical construction, it isto be understood that the construction is not specifically identical and that the fuel flow regulating means 63 and 65 respectively of the high and low speed systems 53 and 61 can be varied from one another, and from one fuel feed housing 27 to another, as desired, to obtain optimum performance for the particular cylinder with which the fuel delivery system is associated. Specifically, and not by way of limitation, various orifice elements can be used and springs or various different characteristics can be used. in addition, the ducts can be sized as desired. in addition, the diaphramn 33 can be of unitary construction or a separate diaphragm can be employed for each fiiel delivery system.

Accordingly, each of the carburetor units 41 is associated with a separate fuel feed housing 27 which can be individually constructed so as to serve the associated crankcase chamber 17 and associated cylinder with optimum performance.

Each fuel feed housing 27 can have a common fuel inlet communicating with each of the high speed-and low speed fuel chambers 33 and 1123, respectively. In addition, the fuel feedhousing 27' can be constructed so that the fuel inlet ducts 91 and 132 communicate through a passage system (not shown) which, in part, extends through the air induction housing 25 for communication with a single fuel inlet line. Alternatively, each fuel feed housing 27 can be individually connected to a fuel source. i a

in operation, fuel flow from the high speed delivery system 53 to the air induction tubes 31 is-controlled by the air flow within the air induction tubes 31. Substan: tially no fuel flow occurs when the throttle valve 39 is closed. However, when the throttle valve 39 is open and the engine 11 is operating at high speed, the flow of air through the air induction tubes 31 causes fuel flow from the high speed nozzles i3.

Fuel flow from the low speed delivery system 61 to the air induction tubes 31 occurs, when the throttle valve 39 is closed, in response to pressure fluctuation occurring in the crankcase chamber 17. Although the low speed fuel delivery system at also serves, when the throttle valve 39 is open, to deliver fuel to the associated air induction tubes 31, the amount of fuel thereby supplied by the low speed delivery system 61 is inconsequential compared to the quantity of fuel delivered by the high speed delivery system 61. The use of a venturi sleeve 37 in the air induction tubes or barrels in the area of the high speed nozzles d3 can be employed to increase the pressures operating on the high speed diaphragm.

As used herein, the term low speed is meant to encompass operation at both midrange and idle speeds as compared to high speeds.

Various of the features of the invention are set forth in the following claims.

We claim:

it. A carburetor comprising an air induction passage,

.a high speed fuel nozzle communicating with said induction passage, a low speed fuel nozzle communicating with said induction passage, a first diaphragm controlled, fuel flow regulating valve communicating with said high speed nozzle and adapted to be connected toa source of fuel, and a second diaphragm controlled,

fuel flow regulating valve communicating with said low speed nozzle and adapted to be connected to a source of fuel, each of said fuel flow regulating valves comprising a diaphragm subject, on one side, to atmospheric pressure, a pivotally mounted lever having one end engageable with the other side of said diaphragm, a fuel inlet valve member connected to the other end of said lever and movable relative to a seat provided in a fuel inlet, and means yieldably urging said lever so as to urge said one end of said lever into engagement with said diaphragm and so as to urge said valve member into engagement with said seat to prevent fuel flow from the fuel source to the associated one of said nozzles.

2. A carburetor in accordance with claim 1 wherein said first and second fuel flow regulating valves have differing operating characteristics.

3. A carburetor in accordance with claim 1 wherein said high speed nozzle comprises a tube having an outlet located approximately in a plane parallel to the axis of said fuel induction passage.

4. A carburetor in accordance with claim 1 wherein said fuel induction passage includes a venturi section and said high speed nozzle communicates with said venturi section.

5. A carburetor in accordance with claim 1 wherein said low speed nozzle comprises a series of axially spaced outlets communicating with said fuel induction passage.

6. A carburetor comprising an air induction housing adapted to be connected to the crankcase of an engine and including a pair of air induction passages each including a high speed fuel nozzle communicating with a high speed fuel inlet port at the exterior surface of said air induction housing and with at least one of said air induction passages including a low speed fuel nozzle communicating with a low speed fuel inlet port at the exterior surface of said air induction housing, and a fuel feed housing adapted to be mounted on said air induction housing in overlying relation to said high and low speed inlet ports and including a first diaphragm controlled, fuel flow regulating valve communicating with said high speed inlet port in said air induction housing and adapted to be connected to a source of fuel, and a second diaphragm controlled, fuel flow regulating valve communicating with said low speed port in said air induction housing and adapted to be connected to a source of fuel.

7. A carburetor in accordance with claim 6 wherein said air induction housing includes a pluralityof said pair of air induction passages and a like plurality of said fuel feed housings respectively associated with said pairs of air induction passages.

8. A carburetor in accordance with claim 6 wherein said fuel feed housingincludes a first removably located orifice element located between said first flow regulating valve and said high speed inlet port and a second removably located orifice element located between said second flow regulating valve and said low speed inlet port.

9. A fuel feed housing adapted to be mounted on a carburetor air induction housing including high and low speed inlet ports, said fuel feed housing including means defining first and second fuel chambers, high and low speed outlet ports adapted to respectively communicate with the high and low speed inlet ports of the air induction housing when said fuel feed housing is mounted on the air induction housing, first and second fuel inlet ducts respectively communicating with said first and second fuel chambers, first and second fuel outlet ducts respectively communicating with said first and second fuel chambers and with said high and low speed outlet ports, a first diaphragm controlled, fuel flow regulating valve in said first fuel chamber, and a second diaphragm controlled, fuel flow regulating valve in said second fuel chamber.

10. A carburetor in accordance with claim 9 including first and second removably located orifice elements respectively located in said first and second outlet ducts and respectively including first and second orifices.

11. A fuel feed housing adapted to be mounted on a carburetor air induction housing including high and low speed inlet ports, said fuel feed housing including first and second members connected to each other in opposing relation to one another, a first pair of first and second recesses in one of said members, a second pair of third and fourth recesses in the other of said members in respective opposing relation to said first and second recesses, a diaphragm member interposed between said first and second members and separating said first and second recesses from said third and fourth recesses, one of said first and second pairs of recesses having communication with the atmosphere and the other of said first and second pairs of recesses constituting first and second fuel chambers, high and low speed outlet ports in one of said members adapted to respectively communicate with the high and low speed inlet ports of the air induction housing when said fuel feed housing is mounted on the air induction housing, first and second fuel inlet ducts in said fuel feed hous- Ing respectively communicating with said first and second fuel chambers, first and second fuel outlet ducts in said fuel feed housing respectively communicating with said first and second fuel chambers and with said high and low speed outlet ports, a first diaphragm controlled, fuel flow regulating valve in said first fuel chamber, and a second diaphragm controlled, fuel flow regulating valve in said second fuel chamber.

12. A carburetor in accordance with claim 1 1 including first and second removably located orifice elements respectively located in said first and second outlet ducts and respectively including first and second orifices.

Claims

1. A carburetor comprising an air induction passage, a high speed fuel nozzle communicating with said induction passage, a low speed fuel nozzle communicating with said induction passage, a first diaphragm controlled, fuel flow regulating valve communicating with said high speed nozzle and adapted to be connected to a source of fuel, and a second diaphragm controlled, fuel flow regulating valve communicating with said low speed nozzle and adapted to be connected to a source of fuel, each of said fuel flow regulating valves comprising a diaphragm subject, on one side to atmospheric pressure, a pivotally mounted lever having one end engageable with the other side of said diaphragm, a fuel inlet valve member connected to the other end of said lever and movable relative to a seat provided in a fuel inlet, and means yieldably urging said lever so as to urge said one end of said lever into engagement with said diaphragm and so as to urge said valve member into engagement with said seat to prevent fuel flow from the fuel source to the associated one of said nozzles.

7. A carburetor in accordance with claim 6 wherein said air induction housing includes a plurality of said pair of air induction passages and a like plurality of said fuel feed housings respectively associated with said pairs of air induction passages.

8. A carburetor in accordance with claim 6 wherein said fuel feed housing includes a first removably located orifice element located between said first flow regulating valve and said high speed inlet port and a second removably located orifice element located between said second flow regulating valve and said low speed inlet port.

11. A fuel feed housing adapted to be mounted on a carburetor air induction housing including high and low speed inlet ports, said fuel feed housing including first and second members connected to each other in opposing relation to one another, a first pair of first and second recesses in one of said members, a second pair of third and fourth recesses in the other of said members in respective opposing relation to said first and second recesses, a diaphragm member interposed between said first and second members and separating said first and second recesses from said third and fourth recesses, one of said first and second pairs of recesses having communication with the atmosphere and the other of said first and second pairs of recesses constituting first and second fuel chambers, high and low speed outlet ports in one of said members adapted to respectively communicate with the high and low speed inlet ports of the air induction housing when said fuel feed housing is mounted on the air induction housing, first and second fuel inlet ducts in said fuel feed housIng respectively communicating with said first and second fuel chambers, first and second fuel outlet ducts in said fuel feed housing respectively communicating with said first and second fuel chambers and with said high and low speed outlet ports, a first diaphragm controlled, fuel flow regulating valve in said first fuel chamber, and a second diaphragm controlled, fuel flow regulating valve in said second fuel chamber.

12. A carburetor in accordance with claim 11 including first and second removably located orifice elements respectively located in said first and second outlet ducts and respectively including first and second orifices.