Page 181
Twin-carburetors
REMOVAL
1.
Unclip the four wire clips for the air box cover,
undo the hose clip at the air cleaner and remove the
cover together with inlet hose.
REMOVING THE FUEL PIPE
b.
6.
Pull off the vacuum hose from the front carburetor.
Remove the carburetor retaining nuts and remove
both carburetors simultaneously.
REMOVING THE Al R BOX COVER
2.
3.
4.
Disconnect the throttle and choke cables from the
carburetors.
Remove the clips from the choke links and remove
the links from the connecting rods.
Remove the air box retaining screws and remove the
box together with flange washers, the throttle cable
bracket and choke connector and the gasket.
REMOVING THE CARBURETORS
DISMANTLING
1. Remove the vacuum chamber cover and spring.
2. Remove the vacuum piston and diaphragm.
3. Undo the locking screw (7) and take out the fuel
needle (8).
As from 1977 model (externally adjustable fuel
needle) first remove the stop screw and then turn the
needle adjuster (at the bottom of the dashpot) anticlockwise using the CO adjustment tool, se enabling
the fuel needle to be removed. (Clamp the needle
sleeve to prevent it turning).
4. Remove the screws, aluminium washer and diaphragm.
5. Remove the float chamber.
6. Carefully separate the float spindle from the retainer and remove the float.
7. Up to and incl. model 1976:
Unscrew and remove the jet retainer together with
the adjusting screws, jet, spring, bushing, 0-ring,
bushing and aluminium washer.
REMOVING THE AIR BOX AND BRACKET
5.
a.
Undo the clips and remove the fuel pipes.
SA.Ml
231-11
Page 182
7. As from model 1977:
The jet is press-fitted into the carburetor and normally does not need to be removed.
replaced. Check the fuel needle for wear; bent or worn
needles should be replaced. Check that the contact and
sealing surfaces are not damaged. Check that the contact
surfaces of the choke device are free of scratches. Clean
the temperature compensator and check that the valve
moves freely.
r1
'
1
I
Changing adjustment screw in the piston
r
(as from model 1977)
1. Using a drift, press out the adjusting screw a few centi-
metres at the bottom of the piston.
2. Press in the adjustment screw again.
3. Turn the locking clip loose and remove it by means
of a bent piece of wire. The adjustment screw can
now be removed .
18
21
•l"'J
:i... qp • • : •'11 t0-1210 ~:
19 20
8
-
0
13-
J-14
15i/
12f16
s-@ ,2-tn
CARBURETOR
1. Damper
2. Vacuum chamber cover
3. Spring
4. Aluminium washer
5. Diaphragm
6. Piston
7. Fuel needle
8. Float
9. Float chamber
*10. Aluminium washer
* 11. Bushing
*12. O-ring
*13. Washer
*14. Spring
* 15. Fuel jet
*16. Jet retainer
*17. Adjusting nut
18. Choke mechanism
19. Temperature compensator
20. Seal
21. ldl ing speed adjusting screw
22. Synchronization sa-ew
Installation
1. Press the adjustment screw with the aid of a drift into
the piston.
Grease the 0-ring with Vaseline or the equivalent
to prevent the ring from being damaged on fitting
by any scoring on the cylinder bore.
*Up to and incl. model 1976.
2. With the aid of a drift press in a new circlip in the
damper cylinder.
8. Remove the float valve and washer.
9. Remove the choke mechanism.
10. Remove the temperature compensator. Save both
rubber gaskets.
Wash the carburetor parts in paraffin.
CAUTION
The diaphragm should only be cleaned with
paraffin.
Avoid using volatile cleaning agents such as
tr ichloroethy lene.
CLEANING
Clean the hole in the choke valve disc by means of compressed air. Check that the diaphragm is not faulty. If
the diaphragm is distorted or has cracked, it should be
231-12
THE CIRCLIP IS PRESSED INTO THE PISTON
u.a
Page 183
CHANGING THE FUEL JET AS FROM MODEL 1977
The fuel jet is press-fitted in the carburetor housing and
should not be moved from the specified position. However, the jet can be changed using tool 8392789 as
follows.
1. Remove the carburetor and then take off the vacuum
chamber cover and remove the vacuum piston and
float chamber cover.
2. Press out the jet using tool 8392789.
ASSEMBLY
1.
2.
3.
Mount the float valve.
Up to and incl. model 1976:
Using a new 0-ring, screw the adjusting screw into
Up to and incl. model 1976:
Fit the spring, washer, 0-ring, bushing and aluminium washer to the jet and mount them together
with the jet retainer and adjusting screw in the carburetor housing. Screw in and tighten the jet retainer. Screw down the adjusting screw until the jet
is 0.098 in. (2.5 mm) below the level of the bridge.
The measurements should be read by means of a
vernier or measuring tool 83 93 027.
MEASURING THE HEIGHT OF THE JET BY MEANS OF A
VERNIER
3. Using the tool, press in the new jet from the float
chamber side until the jet is 2.5 mm below the level
of the bridge in the carburetor housing. If you happen
to press the jet in too far, it can be pushed back from
above using the same tool.
MEASURING THE HEIGHT OF THE JET BY MEANS OF TOOL
83 93 027
4.
CAUTION
Avoid resting any type of measuring tool against
the upper, inner surface of the jet when pressing
it into position. Even the slightest deformation
in the surface can affect the hole in the jet.
5.
SAAB
Mount the float and spindle. The flat side of the
float should be turned away from the carburetor
housing.
Check the float level as follows:
a. In order to check the float level, the carburetor
must be removed from the car and inverted
with the float chamber off.
231-13
Page 184
b.
For the level to be correct, the highest point of
the float should be 0.63-0.67 in. (16-17 mm)
above the edge of the carburetor housing (with
gasket removed). See the illustration for when
the float valve is closed. In the event of the
level not being correct, adjust by carefully
bending the tongue at the float valve.
CAUTION
Do not bend the arm between the float and the
spindle.
CAUTION
If the diaphragm is distorted and will not fit the
groove then it should be renewed.
Place the aluminium washer carefully in position,
checking that the screw holes align with the corresponding holes in the piston and diaphragm and
without twisting the washer. Secure the washer by
means of the screws.
Fit the fuel needle according to the following description.
Up to and incl. model 1976:
The flat milled surface of the spring housing should be
pushed by spring action away from the butterfly when
the piston is fitted to the carburetor.
The fuel needle should be installed so that its plastic
washer lies 0.016" (0.4 mm) under the lower surface
of the vacuum piston.
This way of installation gives initial position for the
coming CO-adjustment.
MEASURING THE FLOAT LEVEL
6.
7.
Fit a new gasket and slide on the float chamber
until it makes contact with the O-ring. Tighten all
screws about two turns and slide the float chamber
into position and tighten the screws.
Mount the diaphragm on the vacuum piston so that
the locating lip engages in the corresponding recess
in the piston and the inner edge fits easily into the
matching groove in the piston.
Needle sleeve flush with
bottom of piston
FITTING THE FUEL NEEDLE, UP TO AND INCL. MODEL
1976
As from model 1977:
Push the needle spring housing into the vacuum piston.
Use the CO adjustment tool to rotate the spring housing
so screwing it onto the adjuster.
S 1694
FITTING THE DIAPHRAGM
231-14
SAAB
Page 185
9.
position as indicated by the markings, insert and
tighten the screws.
Install the choke mechanism. (If the choke mechanism has been dismantled, fit the disc, spindle and
cam as shown in the illustration. The calibrated
holes should face the link fixing point).
❖:❖:;;;:
'.♦•♦.'.♦.'
'.♦•♦,,..,,:
..........
1111111
❖:❖:❖l
FITTING THE FUEL NEEDLE AS FROM 1977 MODEL
Tool 83 92 763 or 83 92 896 (Allen key)
Tool 83 93 035 (recessed slot)
'.1'.1'.1'.1'.t
b. Screw in the lock screw so that the spring loaded
pin presses against the spring housing.
c. Turn the spring housing with the aid of tool
8392763 so that the pin enters the groove.
d. Tighteen tbe lock screw.
e. Adjust the height of the needle using the CO adjustment tool so that the shoulder of the needle
(at the groove for the washer) is flush with the
bottom of the piston.
FUEL HOLES IN CHOKE MECHANISM FACING THE LINK
FIXING POINT
10. Check the setting of the temperature compensator
and that it operates freely (see section "temperature
compensator"), and mount it together with the two
rubber gaskets.
Fill the damper cylinder with oil once the carburetor has
been fitted on the engine.
INSTALLATION
1.
Needle sleeve flush with
bottom of piston
Fit the two gaskets with the insulation between
them to each of the inlet manifold flanges.
S 5607
FITTING THE FUEL NEEDLE, AS FROM MODEL 1977
8.
This way of installation gives initial position for the
coming CO-adjustment.
Install the piston together with diaphragm and
spring in the carburetor housing. Ensure that the
outer lip of the diaphragm engages the matching
recess in the carburetor housing (see illustration).
Place the vacuum chamber cover carefully into
FITTING THE INSULATION WASHERS AND THE GASKETS
TO THE INLET MANIFOLD FLANGES
2.
J
SAAS
Mount the two carburetors simultaneously and
secure by means of the nuts and washers. Ensure
that the spring which keeps the rear carburetor arm
and adjusting screw in contact with the arm of the
front carburetor is fitted.
231-15
Page 186
3.
a. Connect the fuel pipe and fit the clips.
b. Connect the vacuum hose.
4. Mount the gaskets, bracket, air box and flange
washers to the carburetors.
5. Fit the choke links to the connecting rod and fit the
clips.
6. Connect the throttle and choke cables.
7. Fit the air box cover and connect the inlet hose to
the air cleaner. Avoid causing deformation of the
flange by overtightening the clip.
8. Top up the damper with oil. The oil level should be
at least 0.39 in. (10 mm) below the top of the cylinder.
CHECKING THE CLEARANCE, FAST IDLING CAM-ADJUSTING SCREW
ADJUSTMENT
Basic setting, up to and incl. model 1976
Choke mechanism
1.
1.
Check that the two choke mechanisms reach their
stops simultaneously. If necessary, adjust the links
to the connecting rod.
Remove the vacuum chamber cover, spring, and
piston complete with diaphragm.
REMOVING THE VACUUM CHAMBER COVER, SPRING
AND PISTON
ADJUSTING THE CHOKE MECHANISM LINKS
2.
2.
Check that the clearance between the adjusting
screw on the throttle shaft stop arm (front carburetor) and the choke mec.hanism cam is 0.04 in. (1
mm). The choke control should be pushed all the
way in so that the valves are completely closed.
After adjustment of the idling speed, check this dimension and adjust if necessary.
Use a vernier gauge or measuring tool 83 93 027 to
adjust the distance between the jet bridge and the
jet to 0.098 in. (2.5 mm).
MEASURING HEIGHT OF JET
231-16
5MB
Page 187
Up to and incl. model 1976, a special adjusting tool, No.
83 92 995, with insert No. 83 93 001 (designed for twin
carburetors) and a set of feeler gauges, No. 83 93 019,
are available to facilitate adjustment of the fuel needle.
3. Adjust fuel needle heigh position in the piston by
loosening the screw and move the needle up or down.
TOOL FOR ADJUSTING THE FUEL NEEDLE
Needle sleeve 0,015 in
(0,4 mm) below the piston.
Insert the vacuum piston into the tool, with the feeler
gauges inserted in the slots of the tool.
The tool is preset to 0.04 in ( 1.0 mm) and consequently
the 0.06 in (1.4 mm) feeler gauge will provide the basic
setting (i.e. the needle sleeve approximately 0.015 in
(0.4 mm) below the piston).
If during subsequent adjustment of the CO-setting it
proves necessary to lower the fuel needle, use a thicker
feeler gauge, and to raise the needle, use a thinner feeler
gauge.
S 5615
HEIGHT SETTING OF FUEL NEEDLE
\
S 5608
ADJUSTING THE FUEL NEEDLE
Tool 83 92 995
4.
KEEP THE NEEDLE PERPENDICULAR
OF THE PISTON DURING CHECKING
TO THE BOTTOM
~
Install the piston complete with diaphragm and
spring and mount the vacuum chamber cover.
231-17
Page 188
Basic setting, as from model 1977
Synchronizing the carburetors
The jet is fixed in the carburetor. Adjust the height of the
fuel needle by means of the special tool.
1. Remove the plastic cover and damper piston.
2. a. Insert the CO adjustment tool through the dashpot
onto the vacuum piston and adjustment screw.
1.
Run the engine until warm and then let it run at
normal idling speed. The idling speed adjusting
screw serves both carburetors and is located on the
front carburetor.
SETTING THE IDLING SPEED
INSERTING THE TOOL THROUGH THE DASHPOT
Tool 83 92 763 or 83 92 896 (Allen key)
Tool 83 93 035 (recessed slot)
2.
b. Use the sleeve of the tool to support the damper
piston to prevent the diaphragm being damaged.
c. Turn the adjusting key clockwise until resistance
is felt (needle in highest position).
NOTE
If the adjusting screw is seizing, it may be difficult to detect when the needle has reached its
highest position, as described in item C above.
In such cases, we recommend that the vacuum
pistons be removed for making the basic setting.
Accordingly, SET THE HEIGHT OF THE
NEEDLE LEVEL WITH THE BOTTOM OF
THE PISTON.
Needle sleeve flush with
bottom of piston
S 5607
d. Rotate the screw 1 1/2 turns counter-clockwise.
231-18
SAAB
Synchronize the carburetors by means of the adjusting screw on the linkage between the two carburetors. Compare the air flow through the carburetors
by means of a synchro-tester. The adjusting screw
should be locked by means of the lock nut after
setting.
Page 189
,.,,,
THROTTLE SYNCHRONIZATION
DISCONNECTING THE CRANKCASE VENTILATION,
FROM MODEL 1976
SCREW
AS
1. The hose removed from valve cover
2. The small-bore hose plugged (as from model 1977)
3. Evacuation hose connected to valve cover
CO-setting
As from model 1977:
To minimize the possible effects on the setting of
various engine and exhaust emission components,
the CO-setting should be carried out at an engine
speed of 2 000 rev/min.
Evacuate the crankcase gases from the opening in the
valve cover by connecting a hose to the workshop's evacuation hose, slightly behind the probe of the CO-meter
to ensure that the readings will not be affected.
To obviate the possible influence of hydrocarbons on the
CO-setting (caused by the presence of fuel in the engine
oil), the crankcase ventilation should be disconnected
while adjustment work is being carried out.
1. Preparing to measure the CO-setting:
a. Run the engine until it is warm so that the CO-reading (item 4) may be carried out after the radiator
fan has cut in for the second time.
b. Up to and incl. model 1977: Check that the preheater valve is in the "Summer" position.
c. Check that the choke control is fully depressed.
d. Check that the float chamber ventilation valve is
correctly adjusted.
e. Check that the ignition timing is set correctly.
f. Check the synchronization of the carburetors.
g. Plug or clamp shut the vacuum hose to the vacuum
control unit on the distributor.
EVACUATION HOSE CONNECTED TO THE WORKSHOP'S
EVACUATION SYSTEM
i. Plug the end of the vacuum hose to the EGR avlve
where applicable.
2. Connect the CO-meter and tachometer.
THE DISTRIBUTOR HOSE CLAMPED
h. Disconnect the crankcase ventilation as follows:
SA.4\11
231-19
Page 190
S 5202
S 5612
CHECKING THE CO-CONTENT
3. Set the idling speed to up to and incl. model 1976:
850 ± 50 rev/min.
As from model 1977: 2000 rev/min.
THE FUEL NEEDLE IS RAISED OR LOWERED
As from model 1977:
To adjust, remove the dashpot piston and then turn
the fuel needle adjustment screw using the CO adjustment tool. Support the vacuum piston by means of
the sleeve of the tool to prevent the rubber diaphragm from being damaged.
ADJUSTING THE IDLING SPEED
4. Read off the CO-value.
ADJUSTING THE CO-SETTING
Tool 83 92 763
CO-setting with crankcase ventilation disconnected
Up to and including 1976 model
As from 1977 model Sweden
As from 1977 model Europe
max. 3.5% at850 r.p.m.
1. 75±0.25% at 2000 r.p.m.
1.5±1 % at 850 r.p.m.
Up to and incl. model 1976:
To adjust the CO-setting, raise or lower the fuel needle to
increase or reduce the CO-value, respectively. Do not turn
the jet adjusting screws more than 1/4 of a turn from the
basic setting.
Rotate clockwise (A) to increase CO-value (fuel needle
raised).
Rotate counter-clockwise (B) to reduce CO-value (fuel
needle lowered).
5. Remove the plugs and connect up the crankcase ventilation, the EGR hose and the vacuum hose to the distributor.
6. Set the idling speed to 850 ± 50 rev/min.
7. Check the CO-value at idling speed. If the value exceeds 4.5 %, it is likely that fuel has penetrated the engine oil, necessitating an oil change.
CAUTION
Check the calibration of the CO-meter regularly.
231-20