Page 101
Evaporative loss control unit USA cars as from model 1971
As from model 1971, cars for USA-market are fitted with
a charcoal filter, which absorbs the vapor from the fuel
tank. The charcoal canister is placed in the engine com-
partment. It is connected to the vent hose of the fuel
tank and with a hose to the air cleaner. When the engine
is running, fresh air is sucked through the charcoal filter
and further to the carburetor. The filter will then be
cleaned from petrol.
FUEL SYSTEM, CARBURETED ENGINE
1. Fuel pump
2. Air cleaner
3. Carburetor
4. Fuel tank
. Fuel level transmitter
. Drain plug
. Vapor hose
. Charcoal canister
Onan
Jan. 1972 SAAB
200-5
Page 102
Carburetor
The engine is fitted with a Zenith—Stromberg cross-flow
carburetor with the type designation 175 CD—2S. It has
only one jet, the cross-section area of fuel flow being reg-
ulated by a moving tapered needle. The position of the
needle is determined by the negative pressurization of the
carburetor housing, which acts upon a piston in which
the needle is mounted. The needle is of self-centering
type, i.e. it is suspended in springs; this makes it unneces-
sary to adjust the alignment of the carburetor jet.
The carburetor is made of light metal. It consists of three
main sections, the central one being the carburetor hous-
ing. The bottom section is the float chamber, which sur-
rounds the jet. The jet is vertically adjustable. The top
section is the vacuum chamber, the lower boundary of
which is a diaphragm in which the piston is suspended.
The vacuum chamber communicates with the carburetor
inlet duct via two channels in the piston.
The vacuum in the carburetor housing determines the rate
of fuel flow, which is controlled by the needle, as well as
the rate of air flow, which is regulated by the position of
the piston in the air duct. In this way the engine always
receives correctly adjusted quantities of fuel and air under
all load conditions.
S7u3
CARBURETOR
1. Jet adjusting screw
2. Float chamber
3. Cover for vacuum chamber
4, Fuel inlet
5. Vacuum nipple
6. Cap for oil damper
7. Carburetor body
8, Fast idle cam
9. Fast idle screw
10. Throttle screw
Float system
Fuel enters the float chamber through the float valve. The
float, which is double, is located by a bridge on the under-
side of the carburetor housing. As the fuel level rises, the
float rises with it, and when the correct level is reached,
the float valve is closed by a tongue on the float arm.
The fuel passes through four noles in the jet retainer and
four holes in the top of the adjusting screw to the interior
of the jet where it assumes the same level as in the float
chamber. The seals between adjusting screw and jet retain-
er, between jet retainer and float chamber and between
jet and guide are provided by O-rings.
Choke and fast idling
The carburetor is equipped with a choke device for easier
starting of cold engine.
The choke consists of a valve disc which, when the choke
spindle is rotated, opens four fuel holes of different sizes
in succession as well as opening an emulsion air duct and
freeing the choke fuel mizture duct to the carburetor head.
When the choke button is pulled right out, all four fuel
holes are in operation and the emulsion air duct is wide
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CARBURETOR WITH THROTTLE CLOSED
1, Damper cap 10, Adjusting screw
2. Diaphragm 11. Vacuum piston
3. Compensating hole 12. Starting fuel hole
4, Oil damper 13. Throttle
5. Float chamber ventilation 15, Vacuum hole
6. Float valve 15. Fuel needle
7. Float 16. Jet
8. Spring 17, Float cham ber
9. Fuel holes
sete SAAB Jan. 1972
Page 103
mY
open. At intermediate choke positions one or more of
the fuel holes are closed, but the emulsion air duct remains
open as long as any of the fuel holes is open. When the
choke button is pushed right home, this closes both fuel
and emulsion air ducts as well as the starting fuel hole in
the carburetor housing.
Emulsion air is drawn in through a jet from the carbu-
retor housing. Its function is to improve the distribu-
tion of the choke fuel mixture among the cylinders.
The choke spindle carries a cam to which the pull wire of
the choke control is attached. When the car is driven on
the choke, this cam acts upon the throttle control to raise
the engine idling speed during starting and warmup.
Idling
The carburetor has no special idling system. When the en-
gine is idling, the negative pressurization in the vaccum
chamber of the carburetor is low, with the result that the
gap between the vacuum piston and bridge is small. Most
of the jet is therefore blocked by the thick end of the
fuel needle and only a small quantity of fuel, correspond-
ing to the idling demand, is drawn into the engine. The
ratio of fuel to air is regulated at idling speed with the ad-
justing screw, and this setting remains correct for the full
range of engine speeds.
10
CARBURETOR WITH THROTTLE OPEN
1, Damper cap 10. Adjusting screw
2. Diaphragm 11. Vacuum piston
3. Compensating hole 12. Starting fuel hole
4. Oil damper 13. Throttle
5. Float chamber ventilation 14, Vacuum hole
6. Float valve 15. Fuel needle
7. Float 16. Jet
8. Spring 17. Float chamber
9. Fuel holes
Nov. 1972
Normal driving
When the throttle is opened, a vacuum is generated in the
vacuum chamber which is equal to that in the inlet mani-
fold due to equalization via the holes in the piston. As at-
mospheric pressure prevails on the underside of the dia-
phragm, the piston is pulled up and the airflow through
the carburetor is increased. At the same time the fuel
flow also increases as the tapered needle, which is attached
to the piston, is withdrawn from the jet.
Acceleration
In order to produce a temporarily richer fuel mixture on
rapid opening of the throttle (acceleration), a damping
device is provided in the spindle of the vacuum piston.
This consists of a small piston called the oil damper
mounted on a rod. The damper runs in oil. When the
throttle is opened quickly, the negative pressurization in
the vacuum chamber is abruptly increased. When the vac-
uum piston is raised, the oil damper is pressed against its
seating and prevents oil from flowing past from below
the damper to above it; this brakes the movement of the
vacuum piston, temporarily generating a harder vacuum
above the jet and momentarily enriching the fuel-air
mixture.
The downward movement of the vacuum piston is assisted
by a spring. The oil level in the hollow spindle of the vac-
uum piston, should be so high that the oil damper dips in-
to oil before the thread of the screw cap engages the vac-
uum chamber cover. When filling, top up the hollow spin-
dle with oil to its rim. NOTE! Do not fill the space above
the spindle. Use the same oil as in the engine, i.e.
SAE 10 W 40 or 10 W 30, or if the outdoor temperature
is constantly below —4°F (—20°C), SAE 5 W 20.
Overrun braking, 2.0 | engine
The 2.0 | engine has been fitted with an overflow valve
to achieve satisfactory combustion on the overrun. This
type of overflow valve has previously been fitted to USA
export models.
Fuel system, injection engine
The engine is equipped with a Bosch electronic fuel injec-
tion system. An electric fuel pump and a pressure regulator
deliver fuel at constant pressure. The injection valves
supply the four cylinders with an adjusted quantity of
fuel. The fuel is injected into the inlet manifold just in
front of the inlet valves and the fuel feed is depending of
how long time the injection valves are open. This is con-
trolled by an electronic unit and varies according to the
load, speed and temperature of the engine. See also
Section 234.
SAAB 200-7
Page 104
Carburetor, USA export model, 1.7 and 1.85 | engines
The engine is equipped with a Zenith-Stromberg cross-
flow carburetor with the type designation 175 CD—2SE,
This carburetor differs from the 175 CD—2S type in the
following respects:
a. It is fitted with a jet pressed into the housing, which
means that the jet is not adjustable. The carburetor
has a temperature compensator (8) consisting of an
air valve regulated by a bimetal spring which keeps
the fuel-air mixture constant regardless of the tempe-
rature in the engine compartment. The valve begins
to open when the temperature of the carburetor
reaches about +50°F (+10°C), admitting supplemen-
tary air through a channel that issues ahead of the
piston.
b. The carburetor is also equipped with an overflow
valve (5) consisting of a spring-loaded diaphragm
valve mounted in a housing with a cap and adjusting
screw. The negative pressure inside the accelerator
throttle can be transmitted through a channel to the
top of the diaphragm; during overrun braking this
negative pressure is strong enough to overcome the
force of the spring that normally holds the diaphragm
valve shut. The valve then opens to admit through a
channel past the throttle the extra fuel-air-mixture
needed to sustain combustion during overrun brak-
ing.
c. There is also an air screw (3) for fine tuning of the
idling speed.
d. Finally, this carburetor has two vacuum nipples (2)
communicating with the distributor. The upper one
regulates the ignition rise during driving at low engine
load with the engine running above idling speed, while
the lower one cuts in and lowers the ignition when
the throttle is in the idling position.
Carburetor, USA export model, 2.0 | engine
The engine is equipped with the same carburetor as the
2.0 | engine standard design. However, there is no tem-
perature compensator.
$3475
CARBURETOR, USA
. Sealing
Vacuum nipple
. Air screw
Screws for removal, owerflow valve
Overflow valve
Float chamber plug
. Float chamber
. Temperature compensator (only on 1.7 and 1.85 | engines)
. Screws for removal, temperature compensator
OMNAAAWNS
10. Adjusting screw, fast idling
11. Idling screw
12, Vacuum chamber cover
13. Damper cap
14. Air channel, float chamber ventilation
15. Channel, air to space under diaphragm
16. Channel, air to temperature compensator
17. Choke
18. Fast idling cam
19. Connection, choke control wire
Nov. 1972
Page 105
ee.
On AG & WH
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OVERFLOW VALVE, OVERRUN BRAKING
1. Cap washer 8. Diaphragm
2. Adjusting screw 9. Valve
3. Rubber ring 10. Throttle
4, Cover 11. Inlet channel for
5. Nut fuel-air mixture
6. Spring 12. Outlet channel for
7. Channel to top of fuel-air mixture
diaphragm
Jan. 1971 SAA 200-9
Page 106
Air cleaner
The air cleaner is mounted on the carburetor on the left-
hand side of the engine. !t serves both to clean the intake
air and to muftle the intake noise. The filter insert, which
is made of a special grade of paper, must not be washed
or wetted. The only permitted form of servicing is clean-
ing the air filter by tapping it lightly.
The air cleaner is equipped with a valve with two settings.
In the “Summer” setting the air is drawn in direct from
outside, while in the “Winter’’ setting the air passes be-
tween the covers surrounding the exhaust pipe and thence
through a hose to the air cleaner.
Exhaust system
The exhaust system consists of front and rear mufflers,
middle pipe and rear pipe. The middle pipe connects the
two mufflers and is covered on its upper side by a heat
guard bolted to the body floor. The front muffler is at-
tached to the engine exhaust manifold. The rest of the
system is suspended from the body floor by rubber
mountings.
A new exhaust system was introduced in 1972. This con-
sists of two major components: a front pipe attached to
the exhaust manifold and a rear section which includes
two mufflers.
Cooling system
The cooling system is of pressurized type with a cross-
flow radiator and expansion tank. The water pump is
located in the engine block and is powered by a bevel
gear from the idler shaft. The thermostat is located in
a housing bolted to the front end of the cylinder head.
The radiator fan is electrically driven and controlled by
a thermostat. When the pump is working and the ther-
mostat is closed, coolant circulates through the cylinder
block, cylinder head, inlet manifold and heater core.
When the thermostat is open, the pump draws coolant
from the radiator and forces it through the cylinder block,
intake manifold and heater core back through the open
thermostat to the radiator inlet.
A new radiator has been installed on cars from chassis No.
99732031903. The cell package has two rows of cells in-
stead of the former three. But each row contains more
tubes, giving the new radiator greater cooling capacity.
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CIRCULATION IN THE COOLING SYSTEM UP TO AND INCL. MODEL 1970
200-10 SAAB
Dec. 1975
Page 107
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CIRCULATION IN THE COOLING SYSTEM, 1.7 AND 1.85 L ENGINES, MODEL 1971-1972
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CIRCULATION IN THE COOLING SYSTEM, 2.0 L ENGINE, MODEL 1973
Dec. 1975 SAAB
Page 108
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CIRCULATION IN THE COOLING SYSTEM, 2.0 L ENGINE, MODEL 1974
Radiator
Radiator fan
Expansion tank with pressure cap
Thermostat
Temperature transmitter
By-pass line
. Coolant pump
. Fan motor
. Impeller
). Heater core
. Thermostat controlled valve
. Thermostat switch, radiator fan
. Radiator drain cock
. Engine drain cock
SeEernggeone
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200-12 SAAB Dec. 1975
Page 109
Crankcase ventilation
1.7 and 1.85 | engines
2.0 | carburetor engines
2.0 | fuel injection engines up to and incl. model 1973
The engine has a fully enclosed crankcase ventilation sys-
tem. The air is drawn in through the air cleaner and its
filter insert and (on the 1.7 and 1.85 | engines) enters the
oil filler tube via a flame guard and a hose. 2.0 | engines
have a special connection housing with built-in flame
guard through which air passes into the engine block. The
air flows from the crankcase up into the valve cover,
through oil traps and out through a hose to the Smith
valve, which regulates the vacuum in the crankcase. The
air then flows from the Smith valve to the inlet manifold.
Camshaft cover Inlet manifold
Oil trap Valve
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Oil trap
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DIAGRAM OF CRANKCASE VENTILATION, 2.0 L ENGINE
CARBURETOR ENGINES AND INJECTION ENGINES UP TO AND INCL. MODEL 1973
Dec. 1975 SAAB 200-13
Page 110
2.0 | fuel injection engines, model 1974
The pressure in the crankcase is regulated via a T nipple
connected to the inlet manifold. A hose from the valve
cover and a hose from the air cleaner lead to this nipple.
The T nipple contains an orifice plate with a 3.2 mm
bore to give the crankcase the proper vacuum. When the
crankcase pressure is too high, the air flow goes from
the valve cover via a T nipple to the inlet manifold.
When the crankcase pressure is too low, air is drawn from
the air cleaner via the T nipple and into the inlet manifold.
Camshaft cover
Oil trap Inlet manifold T-nipple with restriction
T-nipple with restriction
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Hose from air cleaner
$4126
DIAGRAM OF CRANKCASE VENTILATION, 2.0 L INJECTION ENGINES MODEL 1974
200-14 SAAB
Dec. 1975