Group 23. Fuel System; Description - Volvo 164 1969 Service Manual

GROUP 23
FUEL SYSTEM
DESCRI PTION
The B 30 A engiine is fitted with two horizontal car-
burettors of type Stromberg 175 CD-2SE, the construc-
tion of which is shown in Figs. 2-48, 2-49, 2-50 and 2-51.
Th is type of ca rburettor has been designed with a
view to the exha:ust emission controi system. It is
provided with a fixed jet, pressed into the carburettor
housing, the fuel f low orifice area of which is varied
by means of a· movable tapered needle. The position
of the need le is determined by the carburettor hous-
ing vacuum operating an air vdve in which the
needle is fitted in a springl-Ioaded suspension. The
spring force alwoys presses the need le against the
same side of the jet, and this ensures an accurately
controlled fue l flow through the jet.
The carburettor consists of three inain parts of light-
olloy, the middle part of which comprises the carbu-
rettor housing. The lower section is made up of a
f loatchamber, which encloses the jet and the f loat.
1
2
3
10
4
6
:::;r-----8
7
Fig. 2-48. Carburettor, front, from the left
l. Suction chamber
2. Throttle stop screw
3. Lever
4. Primary throttle
5. Drilling to vacuum side of by-pass valve
6. Drilling for fuel-air mixture from by-pass valve
7. Throttle · s pindle cam (for regulating secondary throttle)
8. Floatchamber plug
9. Floatchamber
10. Fuel inlet
The upper section consists of a suction chamber
cover, which forms a suction chamber together with
a diaphragm fixedin the air valve. The suction cham-
ber regu lates the air vallve
lift
and thereby the loca-
tion of the need le in the jet.
By means of channels in the valve, the suction cham-
ber is linked to the space between the carburettor
throttle and valve.
Both carburettors are fitted with a temperature
com~
pensator (8, Fig. 2-49 and 2, Fig. 2-51). This is con-
structed as an alir valve regulated by the carburettor
temperature and ma,intCliins the fuel-air mixture cons-
tant irrespective of the fuel temperature.
The front carburettor is provided with a throttle by-
pass valve (6, Fig .. 2-49 and Fig. 2-57}, the purpose of
which is to by-pass aregulated flow of fuel-air
mixture PQlSt the carburettor throttle when this is
closed at high speeds.
9
1---~
2-..!!~~
3
8
4
7
5
Fig . 2.49. Carburettor, front, from the rig ht
1.
Venting channel from floatchamber
2. Drilling for air supply under diaphragm
3. Sea led plug'
4. Drilling for air supply to temp. comp . and idle trimming screw
5. Stop screw for by-pass valve
6. By-pass valve
7. Idle trimming screw
8. Temperature compensator
9. Hydraulic damper
2 : 23