Page 101
CARBURETOR FORD, MODE
‘ L 1976~
1977 Sealed mixture adjusting screw, model 1977
General
On mode! 1977, a new type of adjusting screw has been
introduced which is equipped with a seal which must be
removed (and thereby destroyed) before any adjustment
velopment of the can be made.
The adjusting screw must be resealed after adjustment.
The seal comprises a plastic plug which is press-fitted
above the adjusting screw. Plugs mounted at the factory
are white while plugs for use by workshops are blue.
The carburetor has been designed in regard to th i
exhaust emission regulations and isa de si gid
FoMoCo carburetor.
As opposed to the FoMoCo Carburetor, the new carb
retor is equipped with a manual choke, the lower =
sages in the idling system are of new design and te
spray pipe of the main system opens into a venturi-ring
in the carburetor throat,
R, EXPLODED VIEW
aaah a 8. Throttle flap
2. Float chamber cover 4 a se _
a) 3, Float 11. Ball and weight, acceleration fuel passage
po a 12. Fuel line connection
; signa screw, idling mixture 13. Float chamber ventilation
6. Thro’ 5
7. Idling screw
SAAB 200—19
Febr 1977
Page 102
Float system
er is governed by the
at the fuel intake.
the float rises,
The fuel level in the float chamb
float, which acts on the needle valve
As fuel flows into the float chamber, soe a
whereupon the needle valve is pressed against its se cg
shutting off the supply of fuel. When the level drops,
cycle is repeated.
Ventilation of the float chamber is by means
in the float chamber cover and a hose opening In the
right wheel housing.
of a nipple
s
Sse
S 5276
FLOAT SYSTEM
1. Fuel inlet
2. Float valve
3. Float
4. Ventilation
Choke
To facilitate starting when the engine is cold, the carby.
is fitted with a choke valve in the upper part of the
hee retor throat. AS the valve closes, the vacuum below
oe hus the fuel supply, increases.
The choke is controlled manually by means of the choke
control. The choke control cable actuates a lever on the
carburetor. The movement of the lever is transferred yia
a link to a driver on the choke valve pinion.
A fast idling cam which actuates the throttle valve is also
attached to the lever. This is designed to increase the
idling speed during cold-engine starts.
it, and t
2
!
'
ee
CHOKE
1. Choke control
2. Lever
3. Driver, choke valve
4. Choke valve
5. Fast idling cam
6. Driver, throttle valve
publ 1977
——
Page 103
Idling system
A by-pass passage runs past the throt
in an idling spray pipe in the throat
low the throttle valve. The idling pa
pass passage through the idle mixty
When the engine is idling and the t
completely closed (adjusted by th
there will be a high vacuum belo
in the by-pass passage. Accordin
the float chamber, through the
passage to the idling jet, comprising a carefully calibrated
constriction in the passage. The fuel is then mixed with
air introduced through a special air Passage. The mixture
tle valve and Opens
of the Carburetor be-
$Sage Opens in the by-
re control screw,
hrottle valve js almost
€ throttle valve screw)
W the throttle valve and
gly, fuel is drawn from
main jet and idling fuel
then passes through another constriction and pune
air is introduced from a pressure equalizing hole, !o
lower down in the throat of the carburetor. —
This is to ensure a correct fuel-air mixture caine db
ture passes through the mixture control screw an
idling spray pipe and thence to the engine. LS
To improve the transition from the idling syste ihe
main system, two holes connected to the idling ie sh
are located above the idle mixture contro! screw a
throat of the carburetor. As the throttle me wis An
slightly, the holes are opened and additional fu
plied.
IDLING SYSTEM
, Main jet
: Idling fuel passage
dling fuel jet
a ow idling air passage
5, Lower idling air passage
Febr 1977
ene
UU
one
i e
6. Idling passag
7. Idle mixture control screw
8. By-pass passage
ling spray pipe
Bs cca transition system
SAAB
200—21
Page 104
Main system
At higher speeds and heavier loads, fuel is supplied to
the engine through the main system of the carburetor.
The fuel flows through the main jet to the emulsion pipe
which is press-fitted in the carburetor housing. A definite
quantity of air is added to the fuel during its flow past
the emulsion pipe and this quantity is governed by the
emulsion pipe. The fuel-air mixture then flows through
a spray pipe in the carburetor throat. The spray pipe
opens in a ring-shaped inner venturi which provides the
air flow with a corsiderable boost at the spray pipe open-
ing, thereupon producing an effective atomization of the
fuel-air mixture.
The carburetor is equipped with a vacuum-regulated
3
nto ensure that the engine receives a suf¢;.
‘ant fuel quantity at full load. The system comprises g
cien ables connected to the carburetor throat be-
oitte throttle valve by means of a passage. The piston
ig actuated by the vacuum below the throttle valve, When
the engine speed is low and me eirore valve Only slight.
» vacuum is high, the piston is forced up and
d valve located at the main jet is kept closeq,
As the throttle valve approaches stat doentcnna
vacuum drops and the sion casa ec
opening the valve. An additional supply of fuel then flows
into the main system.
booster syste
ly opened, th
a spring-loade
1
LAL
$ 5279
aw Fuel THE MAIN SYSTEM
1. Main jet
Air 2: Emulsion Pipe
ay 3. Emulsicn jet
4. Spray pipe and venturi
MN High vacuum
5. Regulating piston, full-loac boost
6. Valve, full-load boost
7.
Vacuum Passage, booster valve, full-load
Low vacuum
_ SAAR
Fear 1977
Page 105
Acceleration system
jet into the throat of the carburetor.
When the throttle valve is opened repidiyineet When injection ceases and the diaphragm returns to its
dency for the fuel air mixture to adsl das e is a ten- normal position the ball closes the outlet duct and fuel
the fact that the air flows more wavllyy than est eel i the open inlet valve once again fills the acceleration
thus reaches the engine faster. ump.
To compensate for this, a spiel Giant Urtierics A weight is located above the ball in the outlet duct of
jected into the engine by means of the sicéior Is In- the acceleration system and this acts as a non-return
The pump is a diaphragm pump and is pasta ee: pump. valve. The supply of fuel to the acceleration system is
spring-loaded link from the throttle valve ya regulated by means of the certain pressure required to
: lift the ball and the weight. This prevents fuel injection
Fuel for the acceleration system is dr. t f d
is drawn rom th t r i
> e floa
inl when the throttle is opene slowly.
strokes cause the inlet valve to close and fuel is forced
past the ball in the outlet duct, through the acceleration
9 10 s 200
ACCELERATION SYSTEM
1, Acceleration jet 6. Spring
2. Valve 7. Acceleration pump diaphragm
3, Acceleration fuel duct 8. Lever
9. Linkage
4. Pressure equalizing hole
5. Inlet valve 10. Throttle valve
SAAB 200—23
Febr 1977
Page 106
Deceleration system, cars for the USA as from model
1970 and cars for Sweden model 1976 and 1977
The deceleration system comprises a system of passages
inside the carburetor, and a deceleration valve outside
the carburetor mounted in the flange between the car-
buretor and the inlet passage.
A spring-loaded diaphragm is located inside the bottom
cover of the overrun valve; the vacuum in the inlet duct
acts on the top of the diaphragm while atmospheric pres-
sure from a hole in the bottom cover acts from below.
ne deceleration (freewheel locked), the vacu-
During eng! op of the diaphragm is sufficiently high to
um acting seer the spring, thus drawing the diaphragm
exceed ae actuates the valve spindle and the valve
upwards. caction ts thereby made between the inlet
opens. ae deceleration section of the carburetor. The
duct ale fuel-air mixture required to ensure sufficient
= cue during engine deceleration can thus flow
co
through this passage.
5 sei
DECELERATION SYSTEM
1, Air inlet
2. Deceleration air Passage
3. Deceleration fuel Passage
4. To the inlet Pipe
5. Diaphragm
6. Valve
7, Adjusting screw
8. Spring
200~24
Febr 1977
Page 107
CARBURETOR SOLEX, AS FROM MODEL 1977 g
The carburetor comprises three main parts: The carburet
or cover, the carburetor housing and the throttle sectio 4
at the bottom. The carburetor is of the two-stage type F
with primary and secondary stages. The Primary stage ia
cludes the cold-start, idling and acceleration-enrichment
functions. The two throttle valves are mounted in a sepa-
rate throttle valve section underneath the carburetor aie
ing. The throttle valve linkage is arranged in such a way
that the secondary throttle valve will not open until the
primary throttle valve is about 3/4 open, The two valves
reach the full-throttle position simultaneously.
Float system
The level of fuel in the carburetor is regulated by the
float.
When fuel enters the float chamber, the float will rise,
Pressing the needle valve into its seating. When the float
reaches the predetermined level, the supply of fuel will
be shut off. When the level drops, the valve opens and
the cycle is repeated. Ventilation of the float chamber is
by means of a valve in the carburetor housing. Operation
of the valve is governed by the position of the throttle
valve lever. When the throttle is open, the ventilation sys-
tem will operate internally. When the engine is at idling
speed or at a standstill, the ventilation will be external
into the ambient air.
d \ | 5 6 7 8 10
BAIT Nga
° <r ene.
13. N «OTN trod
tT =s=Es t
16 16 17 18 19 20 “~? 21 22 23
CARBURETOR
1. Air jet, main system
2. Ventilation pipe, float chamber ventilation
3. Air jet, transition system
4. Fuel jet, transition system
5. Air jet, main system
6. Choke valve
7. Air passage, idling system
8. Vacuum passage
9. Step cam, fast idling
10. Driver
Febr 1977
11. Adjusting screw
12. Diaphragm
13. Spray pipe
14. Air passage, transition system
15. Throat ring
16. Throttle valve
17. Emulsion pipe
18. Main jet
19. Emulsion pipe
20. Main jet
11° ¢ 12
26 27 28
21. Throttle vaive
22. Mixture adjusting screw, idling
23. Idling adjusting screw
24. Vacuum passage
25. Idling jet
26. Push rod, fast idling
27. Bi-metal spring, automatic choke
28. Stop lever, fast idling
200—25
Page 108
Starting system
The carburetor is fitted with an automatic choke to facil-
itate cold starting. The choke mechanism is actuated by
depressing and releasing the accelerator before starting.
The choke is controlled automatically by means of a bi-
metallic spiral spring regulated by the temperature of the
coolant. When the engine is cold, the choke valve will be
partially or completely closed, depending on the ambient
temperature, but will gradually open as the temperature
trises. The automatic mechanism also in-
he function of which is to increase
the idling speed during cold starting. The step cam is re-
gulated by means of a bi-metallic spring. A vacuum-regu-
ed diaphragm opens the choke soon after starting by
lat of a thrust rod, in order to ensure that the engine
al recalve a sufficient quantity of air when it is running.
To ensure a sufficient supply of air also when the vacuum
drops as 4 result of the throttle having been opened, a
stop is provided on the linkage from the throttle, which
forces the choke valve to open under these conditions.
of the coolan
cludes a step cam, t
g
FY LT SE REP OG ETE LT LIE SO
So NSA SS
sf
a awnnenes nee nnns’ /
een nnn wnen nn ee ant
10
STARTING SYSTEM
1, Float
2. Choke
3. Driver, choke valve
4. Diaphragm, vacuum control
5. Diaphragm rod
200-26
$5771
6. Step cam, fast idling
7. Stop lever, fast idling
8. Vacuum passage
9. Throttle valve
10. Main jet
Febr 1977
Page 109
. to the
ili ture screw
‘ei Falling the idling mix i
Loin AR SERPEE yt oy the blows ween transition to the main ssa
engine. To ensure smo ; he idling mix-
vac calibrated holes are Susie oe from the
m
Sc: nd the fuel/air tats
ture adjusting screw, a e throttle
idling aun flows through these when th
open.
Fuel is drawn through the main
owing to che high vacuum prese
valve during idling. The idling je
admitted through special calibr
of the carburetor. The fuel/air
jet up to the idling jet
nt beneath the throttle
t mixes the fue! With air
ated holes in the throat
mixture is then sucked
veenee
- ppt:
a / Fic $6772
M
IDLING AND TRANSITION SYSTE
1. Main jet
hrottie valve ; Pe.
Fi a adjusting screw, idling
4. Idling jet
| = Primary stage
200-27
SAAB
Febr 1977
Page 110
Main system
Under increasing engine speed and heavier loading, the
engine is supplied with a greater quantity of fuel/air by
means of the main system.
Initially, this is achieved by means of the primary stage
only. The fuel flows from the float chamber through the
main jet and emulsion pipe —where it is mixed with a
given proportion of air — and thence to the spray pipe in
LLL
3
the carburetor throat. When the throttle valve in the pri-
mary stage approaches the full-throttle position, it actu-
ates the throttle valve of the secondary stage by means
of a lever, thereby bringing the secondary stage into op-
eration. Calibrated holes are provided in the carburetor
throat at the same level as the throttle valve, and the
fuel/air mixture is sucked through these holes from spe:
cial transition jets in order to achieve smooth transition
to the main system of the secondary stage.
Lh Addeddededdd
SSST SSS SS
c
$6177
4
MAIN SYSTEM, PRIMARY STAGE
1. Air jet, main system
2. Spray pipe
3. Main jet
4. Emulsion pipe
5. Throttle valve
| = Primary stage
11 = Secondary stage
200-28
Nov 1977