Carburetor attachment

A carburetor attachment is designed for replacing a main jet(s) found in the float chamber of a carburetor. The attachment comprises an elongated tubular member with a bore running therethrough and presenting an opening at the lower end thereof. Threads at the lower end of the tubular member fasten the attachment to the threaded socket presented by removal of the normal main jet. In place, the upper end of the attachment extends above the normal level of the fuel found in the float chamber and has a port thereat providing communication between the internal bore and the surrounding ambient air. An inclined port adjacent the lower end of the tubular member provides a conduit between the surrounding fuel and internal bore. Upon actuation of the carburetor the resulting suction presented within the bore draws the surrounding ambient air and fuel through the respective ports for admixture therein. The resulting mixture is drawn through the opening for subsequent conveyance, through conventional passage means, to the main body of the carburetor.

BACKGROUND OF THE INVENTION 
This invention relates to an improvement in a carburetor for an internal 
combustion engine, and more particularly, to a carburetor attachment 
designed to replace the conventional main jet(s) found in carburetors. 
It is known that the extent of combustion of fuel in the cylinders of an 
internal combustion engine and resulting engine performance is dependent 
upon the quality of the fuel/air mixture drawn therein. Accordingly, 
various devices have appeared either as attachments to the outside of the 
carburetor or as modifications incorporated therein to increase the degree 
of atomization of the mixture delivered by the carburetor to the engine. 
The external devices have included structures for use of rotating vanes, 
fans, blades and the like interspersed between the carburetor and the 
intake manifold so as to further excite and atomize the mixture passing 
therethrough. 
Known devices, internal to the carburetor itself, have included apparatus 
such as nozzles, aspirators and the like interspersed, all or in part, in 
the main venturi of the carburetor so as to provide a more fully atomized 
mixture to the associated internal combustion engine. 
The above devices, although assumed to be effective in their functions have 
resulted in relatively complex and expensive structures and/or 
modifications which must be made to the conventional carburetor. Such 
attributes have hindered their acceptance due in part to the 
cost-effectiveness involved. 
The present invention pertains to the use of an elongated tubular 
attachment designed to replace the main jet found in the float chamber of 
a carburetor. The attachment having an elongated bore functioning as a 
mixing chamber therein has a port at the upper end thereof positioned so 
as to be above the normal level of fuel found in the float chamber. Upon 
actuation of the carburetor, the resulting suction draws the ambient air 
surrounding the upper end through this orifice and into the internal bore. 
Concurrently, fuel is drawn through a lower port positioned adjacent the 
lower end of the attachment so as to be below the normal fuel level. The 
introduction of the air into the chamber via the top port concurrent with 
the entry of the fuel therein causes a preatomization of the fuel/air 
mixture prior to discharge from the attachment for conveyance to the main 
body of the carburetor. This mixture being atomized prior to discharge 
into the main venturi of the carburetor enables a fuel/air mixture of high 
quality to be ultimately injected into the associated internal combustion 
engine. 
It is therefore a general object of this invention to provide an attachment 
for a carburetor which is effective in increasing the quality of the 
fuel/air mixture delivered to the associated internal combustion engine. 
Another object of this invention is to provide an attachment, as aforesaid, 
which is susceptible of use with most conventional carburetors. 
A further object of this invention is to provide an attachment, as 
aforesaid, which is designed to replace the main jet of a carburetor. 
Still another object of this invention is to provide an attachment, as 
aforesaid, which is easily installed in and removed from the float chamber 
of a carburetor. 
Another object of this invention is to provide a carburetor attachment, as 
aforesaid, equipped with a chamber for mixing fuel and air drawn therein 
so as to provide a preatomized fuel prior to entry into the main venturi 
of the carburetor. 
A still further object of this invention is to provide a carburetor 
attachment, as aforesaid, which increases gasoline mileage, engine power 
and reduces carbon build up in the associated internal combustion engine. 
Another object of this invention is to provide a carburetor attachment, as 
aforesaid, which is economical to manufacture and has no moving parts and 
is therefore durable and long-lived. 
Other objects and advantages of this invention will become apparent from 
the following description taken in connection with the accompanying 
drawings, wherein are set forth by way of illustration and example a 
preferred embodiment of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Initially it is to be understood that the carburetor attachment 10, as to 
be subsequently described, is adaptable for use with conventional 
carburetors. Accordingly, the drawings are relatively diagrammatic as they 
are intended to show only those parts needed for a proper discussion of 
the present invention. 
Referring more particularly to the drawings, the attachment 10 as shown in 
FIG. 3, comprises a generally elongated tubular member 12 with a central 
bore 14 running therethrough which presents an opening 16 at the lower end 
18 thereof. Member 12 is threaded 22 at the lower end 18 below an annular 
seating flange 36. 
As shown in FIG. 2, the threads 22 are designed to engage a threaded socket 
24 which is presented by removal of the main jet 26 normally found in 
carburetor 48. Slot 28 at the upper end 20 of member 12 enables a screw 
driver to fit therein for easy insertion of the attachment 10 into socket 
24. 
As shown in FIG. 2, the bottom surface of seating flange 36 is contiguous 
to the floor 46 of float chamber 30 to prevent seepage of the surrounding 
fuel 66 from the float chamber 30 into passage 32. Also, it is preferred 
that flange 36 be displaced from the lower end 18 so as to place the 
opening 16 in effective communication with passage 32 found in the normal 
carburetor. This passage 32 communicates the float chamber 30 with the 
main body 34 of the carburetor. 
At the upper end 20 of attachment 10 is located an air inlet port 38 for 
communicating the bore 14 with the surrounding ambient air. Adjacent the 
lower end 18 of attachment 10 is a fuel inlet port 40 for conducting the 
surrounding gasoline fuel from the float chamber 30 into the central bore 
14. As shown, it is preferred that port 40 is downwardly inclined so as to 
allow the gasoline to flow freely therethrough. Port 40 should be of a 
diameter corresponding to aperture 42 found in the replaced main jet 26. 
Air port 38 is preferrably of a smaller size than port 40, the purpose of 
which is to be subsequently explained. 
Prior to the above discussed replacement of jet 26 with attachment 10, it 
may be necessary to trim the float 44 found in float chamber 30 so as to 
prevent rubbing of this float against the sides of the attachment 10 when 
in place. Also, it may be necessary to adjust the float 44 so that the 
normal fuel level will rise above the opening presented by fuel port 40, 
but not above the opening presented by air port 38. 
Upon fastening the attachment 10 to socket 24, the top cover (not shown) of 
the carburetor 48 can then be mounted thereto. Operation of the internal 
combustion engine creates a vacuum at the intake manifold used to actuate 
the carburetor 48. Such vacuum creates a suction within the bore 14 so 
that the ambient air surrounding the upper end 20 of the attachment 10 is 
drawn through the air port 38 into the bore 14. Concurrently fuel is 
conducted by the suction through port 40 into bore 14. Bore 14 in reality 
is now a vacuum chamber mixing the fuel and air so as to provide an 
atomized fuel/air mixture upon discharge from opening 16. It is preferred 
that port 38 be vertically disposed, as shown, to allow an optimum amount 
of ambient air to be drawn into bore 14. Also, the elongated cylindrical 
configuration of chamber 14 has been found to be effective in causing an 
optimal mix with the injected fuel. Upon discharge the mixture is 
introduced into passage 32 for subsequent conveyance to the main body 34 
of carburetor 48. 
Because of this introduction of air and fuel into the bore or mixing 
chamber 14, it is preferred that the size of air port 38 be smaller than 
the fuel port 40 so that the drawn air does not override the ability of 
the fuel to enter the bore 14 through port 40. Otherwise, it has been 
found that the engine will cut out due to the scarcity of fuel in the 
atomized mixture and, thus, will cause poor engine performance. 
In some cases, especially in late model carburetors using a vacuum to 
expend fumes from the float chamber 30, it may be necessary to vent the 
carburetor float chamber 30 through the top cover (not shown) to 
atmosphere. This vent will provide a sufficient amount and quality of 
ambient air surrounding the upper end 20 necessary for effective function 
of the attachment 10. However, it is preferred that the attachment 10 
itself remain entirely within the float chamber 30. 
The attachment 10 in place does not interfere with the functioning of the 
carburetor 48 and the proper tuning thereof. Because of the 
pre-atomization of the fuel, readjustment or tuning of the carburetor is 
normally required. However, the absence of moving parts and the 
replacement function of attachment 10 enables one to tune the carburetor 
48 with no change in the mechanics of the tuning procedure. It has been 
found that the attachment 10 by providing such an improved air/fuel 
mixture contributes to an increase in the performance of the associated 
engine including improved acceleration and gas mileage and is effective in 
reducing carbon buildup. 
An alternative embodiment of attachment 10 is shown in FIG. 5 to be used in 
those carburetors where the normal main running jets are in the side of 
the carburetor float chamber. A primary metering body 50 for a 4-barrel 
Holley carburetor is shown with the alternative embodiment 52 in place. 
The primary main jets have been removed and attachment 52 inserted into 
the presented sockets 62. As can be seen in FIG. 6, this embodiment 
consists of the elongated member being configured to present first and 
second tubular sections or legs 54 and 56 normal one to the other with the 
internal bore 64 correspondingly running therethrough. Although shown as 
an integral structure, it is understood that legs 54 and 56 can be 
separate elements fastened one to the other. Bore 64 presents an opening 
68 at the free end of leg 54 so that upon insertion into sockets 62 as 
presented by the removed main jets, the opening 68 communicates with 
passage 70. Passage 70, as diagrammatically shown, conveys the fuel from 
the float chamber to the main body of the carburetor via the metering body 
50. Air port 58 is inserted at the top end of leg 56. Fuel inlet port 60 
is inserted near the juncture of the horizontal leg 54 with the sockets 62 
of primary metering body 50. Upon attachment of this metering body 50 to 
the main body of the carburetor this alternative embodiment 52 functions 
in a manner as above described with the same accompanying advantages and 
results. 
During tests conducted on the above carburetor attachment 10 I have found 
that certain improvements made in the design of this carburetor attachment 
10 can elevate its performance. Accordingly, I have found a redesign of 
the mixing chamber 14 of the original attachment 10', as shown in FIG. 7, 
offers improvements thereto. In this embodiment 10' the original mixing 
chamber 14 now consists of an upper air shaft 100 in communication with a 
lower air shaft or mixing chamber 102. The air shaft 100 is of a smaller 
cross-sectional area than the chamber 102 to assure that the volume of 
drawn air entering the mixing chamber 102 does not override the ability of 
the fuel to enter the mixing chamber 102 through the port 104. 
Fuel inlet port 104 now presents a slight horizontally extending and flared 
recess 106 in communication with an upwardly extending channel 108. This 
particular design enables the fuel to lie in the recess 106 before being 
drawn through the channel 108 and into the chamber 102. This channel 108 
has now been upwardly slanted so that the fuel drawn into the mixing 
chamber 102 is due to the air being drawn through the air shaft 100 and 
not other factors. This upward extension of the fuel channel 108 provides 
for a better air/fuel mixture as the fuel and air are arriving in chamber 
102 at approximately the same time. 
Accordingly, I have found that this interior configuration provides for and 
maintains a good fuel mixture under low vacuum in the carburetor.