(from Weber General Catalog 1/5/1961)
fuel arrives through the needle valve (1) to the bowl (4) where the float
(3) controls the opening of the needle (2) in order to maintain a constant
fuel level. Through the ducts (6) and the main jets (5), it reaches the
emulsioning tubes (12) from which after having been mixed with the air
coming from the air corrector jets (11), through the pipes (10) and
the nozzles (7) it reaches the carburation area consisting of the auxiliary
Venturi's (8) and chokes (9).
The fuel flowing from
the bowl (4) arrives to the starting device through the ducts (32) and
the starting jets (30). Emulsified with the air coming from the hole (29)
it reaches the valves opening (35) through the ducts (31) and definitely
emulsified by the air entering from orifices (34) is then carried by means
of the ducts (33) to the carburetor throats below the throttles.
Engine cold starts:
starting device inserted (position A)
Engine starts half warm: partial insertion
of the device (position B)
Engine warm ups: during engine warming
up, even if the vehicle is under way, the starting device must be gradually
pushed into the rest position.
Normal operation: starting device must
be pushed back as soon as the engine has reached the operating temperature
Operation and Progressive Action
The fuel is carried from the bowl (4) to the calibrated holes of the
idling jets (14) through the ducts (15). Emulsified with the air coming
from the ducts (13) through the ducts (20) and the idling feed holes (18)
adjustable by means of screws (19) the fuel reaches the ducts (20) the
mixture can reach the carburetor throats also through the progression holes
By closing the throttle valves, the lever (25) , by means of the shaft
(27), lifts the piston (26). the fuel is thus drawn from the bowl (4) into
the pump cylinder through the suction valve (23). By opening the throttles,
the shaft (27) is free and the piston (26) is pushed down under the action
of the spring (28), by means of the ducts (22) the fuel is injected into
the carburetor throats. The inlet valve (23) is provided with a calibrated
hole which is discharges the excess fuel delivered by the accelerating
pump in to the float bowl.
SETTING THE FLOAT
NOTE: the operation of leveling of the float must be carried out whenever
it is necessary to replace the float and needle valve: in this case it
is advisable to replace also the sealing gasket, making sure that the new
needle valve is tightly screwed in its housing.
1 Make sure that the weight of the float is the correct one (26
grams), that the float can freely slide on the axis and does not
show any pits.
2 Make sure that the needle valve (v)
is tightly screwed in its housing and that the pin ball (Sf)
of the dampening device incorporated in the needle (S)
is not jammed.
3 Keep the carburetor cover (C) in
a vertical position as indicated in the above figure, since the weight
of the float (G) could lower the pin ball
(Sf) fitted on the needle (S)
4 With carburetor cover (C) in vertical
position and float clip (Lc) in light contact
with the pin ball (Sf) of the needle (S)
the distance of both half-floats from upper surface of carburetor cover
(C) with gasket (Gz)
in place, must measure 8.5mm.
5 After the leveling has been done, check that the stroke of the
float is 6.5mm. If necessary adjust the position
of the lug (A).
6 In case float (G) had not been
rightly set, rectify the position of float clip (Lc)
till the required quota is reached, taking care that the clip (Lc)
does not show any pit on the contact surface that could affect the free
sliding of the needle.
7 Fit up the carburetor cover making sure that float can move
with out any hindrance or friction.
5. Idle jet holders 7.
Idle air orifices 16. Additional Air
Horns 18. Pump inlet valve 29.
Idle mixture adjustment screws 30. Pump
jets 34. Pump control rod
39 Spring guides and retainers 42.
Mixture ducts 43. Starting Jets
45. Starting jet wells 61.
Pump deliver vlave 62. Progression holes
inspection screw 63. Emulsion tubes
complete with main jets and air corrector jets 64.
Air Horns mounting plate. 65.
Bowl plate 66. Idle speed adjusting screw 66.
Idle speed adjusting screw 67.
Throttle control lever 68. Retainer
Washers 69. Pump Spring retainer plate
70. Throttle return spring retaining plate
I highly recommend you buy and use the Weber Service Manual for
DCOE carburetors! It gives detailed pictures on how to repair your Weber
carbs. If you want to know more about the way Webers work, you purchase
the book on Weber Theory. Try your local book stores or Autobooks in Michigan.
This web site was created using Weber printed materials and copied
credit is here by given to E.Weber, Bologna Italy
This page created 4/8/98-revised 4/22/00