Volvo B16B Setup guide

REPAIR INSTRUCTIONS
To obtain the best engine performance, before
adjusting the carburetors, make sure that the
distributor dwell angle and ignition timing are
correct. The ignition timing should be checked
and adjusted by using a stroboscope with the
engine running at rapid idling speed and the
vacuum regulator disconnected.
I n addition to this, the spark plugs, ignition cables
and other ignition equipment should also be check-
ed. See the correct values in the specifications.
The instructions below concern only the carbure-
tors for the B 16 B engine. The Service Manual
for cars and vans, Part 1, B 16 A Engine should
also be used where applicable.
FUEL SYSTEM
Carburetors
The hollow spindle on the suction chamber piston
i s filled with oil and functions together with the
small damping plunger (3, Fig. 8) as a damper.
This should be topped-up with oil at regular inter-
vals, for example when the engine oil is changed.
Screw off the nut at the top of the suction
chamber, lift up the nut and the damping plunger
and top-up with oil through the hole. Fill only the
centre spindle so that the oil does not run over
when the piston is fitted. Use SAE 20 engine oil.
Fig. 12.
Float chamber disassembled.
Fig. 13. Jet unit disassembled.
1. Washers 6. Float
2. Nut
7. Float chamber
3. Float chamber cover 8. Pin
4. Strainer with spring 9. Lever
5. Gasket 10. Needle valve
1. Washer
2.
Seal washer
3. Lock nut
4. Spring
5. Adjuster nut
6. Jet
7. Link rod
8. Link
9.
Lever
10. Spring
11. Washer
12. Lower jet bearing
13. Seal ring
14. Washer
15. Spring
16. Washer
17. Seal ring
18. Upper jet bearing
19. Washer

Fig. 14. Suction chamber dismantled.
REMOVAL
1.
Blow the carburetors externally.
2.
Loosen and remove the air cleaners and the
control retainer with the control rod between
them.
3. Remove the fuel line connections and the
vacuum line connections (to the distributor).
4.
Loosen the nuts in the connections on the
shaft between the carburetors. Move up the
connections on the shaft. Loosen the throttle
controls. Remove the carburetors.
Disassembly and cleaning
FLOAT CHAMBER
1. Loosen the float chamber from the carburetor
housing.
2. Remove the nut on the float chamber cap.
Remove the cap and lift out the float. See
Fig. 12.
3. Remove the float lever by pulling out the pin
upon which it pivots.
4. Loosen the needle valve in the cap and the
hollow bolt and strainer.
Fig. 15. Jet unit assembled.
1.
Jet and associated parts
JET UNIT
1.
Remove the return spring for the jet lever
and the link rod between the lever and the
cam-shaped plate.
2. Remove the bolt for the jet head and the
upper bolt for the link and then remove the
l ever. See Fig. 13.
3. Remove the lock nut and take out the jet
bearings with the spring and gland. Pull out
the jet. Screw off the adjuster nut and remove
i ts spring.
SUCTION CHAMBER WITH PISTON
AND FUEL NEEDLE
The suction chamber and the piston are matched
as units and if one of these is replaced then the
other must be replaced at the same time. The
suction chamber has three attaching screws which
are staggered to ensure that it is fitted the right
way.
1.
Remove the damper (1 Fig. 14) from the suction
chamber.
2. Loosen the screws on the suction chamber and
lift it out.
3. Lift up the spring and the piston. Take care to
ensure that the needle is not damaged (bent).
4. Screw out the lock screw on the fuel needle
and pull it out.
1. Damping plunger 4. Washer
2. Suction chamber 5. Spring
3. Piston

CLEANING
After disassembly, all parts should be cleaned
i n kerosene or alcohol and then blown clean with
compressed air.
Fig. 16. Checking fuel lever.
1. Gauge SVO 2324

2. Float chamber cover
Fit of suction chamber piston
Test this fit when the carburetor is disassembled
and cleaned.
1.
Screw in the damping plunger but do not fill
with oil.
2. Plug the hole in the lower part of the plunger
at the needle.
3.
Place the piston in the chamber (without spring)
and turn the chamber upside down.
4.
Measure the time taken by the piston to sink
from the upper edge level of the large part.
The time taken is normally 5-7 seconds.
ASSEMBLY AND FITTING
Assembly and refitting on the engine is carried
out in the reverse order to that used when dis-
assembling and removing.
Before assembling, check that all gaskets and
sealing glands are free from damage. Replace
these if necessary. Make sure that all other parts
are neither damaged nor worn.
Neither the suction chamber nor the piston may be
filed or rubbed with emery paper since this will
change the fit and this has been very carefully
calculated so that the carburetor will function
properly. Any small unevenness can, however, be
carefully rubbed away.
When attaching the needle in the piston it is very
Fig. 17.
Attachment of fuel needle.
A=attaching level
i mportant to ensure that the needle assumes the
right depth. See under the heading "Replacement
of fuel needle".
Do not tighten the float chamber hollow screws
too hard otherwise the gaskets can be damaged.
The piston in the suction chamber is grooved and
a guide projection in the carburetor housing fits
i
nto this groove. Lubricate the piston spindle
l i ghtly with thin engine oil before reassembling.
The jet must be centralized before it is tightened.
See under the heading "Centralizing the jet".
Add oil (engine oil SAE 20) to the damping cylin-
ders after reassembling the carburetors.
The shaft between the carburetors should be fitted
so that there is a small axial clearance at both
ends. Make sure that the fuel pipe between the
carburetors is curved upwards when tightening the
hollow bolts so that the carburetor levers are free
at full throttle.
Checking the fuel level
The fuel level can be checked indirectly after re-
moving the float chamber cap.
1. Loosen the fuel line and remove the float
chamber cap.
2. Turn the float chamber cap upside down.
3. Measure the distance from the float chamber
cap to the lever by means of gauge SVO 2324
as shown in Fig. 16. When the needle valve
i s closed, the needle valve lever should just
contact the gauge.
4. I f necessary, bend the lever where it joins
the yoke-shape section in order to maintain
the clearance mentioned in point 3 above.

Replacement of fuel needle
1. Remove the suction chamber and the piston
and fuel needle.
2.
Loosen the screw on the fuel needle and pull
out the fuel needle.
3.
Fit a new fuel needle. Check that this is marked
as mentioned in the Specifications. Push the
needle so far into the piston that only the
tapered working section is outside it. See
Fig. 17. Tighten the lock screw.
4. Fit the parts into the carburetor. Then check
that the piston moves easily up and down.
The piston can be lifted slightly without having
to remove the air filter with the help of the
pin (11, Fig. 5). When the pin is slowly released,
the piston should be heard to meet the bridge
with a characteristic sound.
Replacement of jet
1.
Remove the jet as described under the heading
"Disassembly and cleaning, jet unit". The ad-
juster nut does not need to be removed. If
the carburetor is fitted on the engine the wire
on the jet lever should be loosened.
2. Fit the new jet in the lower bearing and then
fit
the lower seal washer and packing, the
spring, the upper seal washer with packing and
the upper bearing with its copper washer. The
brass washers for the upper and lower seals
should be in contact with the spring.
Fig. 18. Centralizing the jet.
Fig. 19. Setting the adjuster nut.
3. Push in the jet together with the assembled
parts into the carburetor housing, see Fig. 15.
Screw on the lock nut loosely. Centralize the
j et as shown below and then fit the lever and
the other disassembled parts.
Centralizing the jet
I
n order to ensure that the carburetor functions
i n the correct way it is extremely important to
make sure that the fuel needle moves easily up
and down in the jet without jamming against the
walls of the jet. For this reason a very careful fit
(centralizing) of the jet relative to the fuel needle
i s necessary.
The jet bearings are attached with quite a large
L ateral clearance so that they can be moved
l
aterally when adjustment is carried out.
1. Remove the air cleaner, damping plunger and
suction chamber with piston. Then fit only the
suction chamber.
2. Loosen lock nut for jet sleeves (5, Fig. 6).
Unhook the spring at the lever and pull out
necessary cotter pins and bolts so that the
l ever can be turned out of the way.
3. Slide the centering tool SVO 2369 into the
carburetor as shown in Fig. 18. The narrow
end of the tool should then press down in
both jet sleeves and press out the jet.
1. Adjuster nut
2. Lower part of jet
3. Wrench

4. Tighten the lock nut with the tool pushed fully
down and then turn the tool to see if it moves
easily. It may be necessary to loosen the nut,
turn the tool and tighten the nut several times
i n succession to obtain a good result.
5.
The tool should then be pressed up by the jet.
This protects the jet sleeve washers. Remove
the tool. Fit the bolts for the lever and the
return spring. Lift the outer end of the lever,
release it and check that the jet is pushed
up by the spring.
6.
Fit the carburetor parts except the air cleaner.
Check that the piston operates easily by lifting
and releasing it. When released, it should strike
the bridge with a slight bang.
7. Fit the air cleaner making sure that the gasket
i s turned correctly so as not to block the ven-
tilation holes. Add oil to the damping cylinders.
Set the adjuster nut as described below.
I
dling settings and the coupling together
of the carburetors
I
dling setting is carried out partly by means of the
screws (3 and 7, Fig. 4) on the throttle arms which
regulate engine speed, and partly by turning the
adjuster nuts on the jet heads (1, Fig. 19) whereby
the richness of the fuel mixture is altered. When
the nuts are screwed down, a richer fuel mixture
i
s obtained. If the nuts are screwed up the mixture
will be leaner. The richness of the mixture is set
during idling to cover the whole speed range of
the engine.
When the correct idling speed has been obtained
and both carburetors have been adjusted to the
same level, they are then connected together.
I ndividual settings should be carefully carried out
before the carburetors are connected together in
order to get the highest output from the engine.
1.
Run the engine until it is thoroughly warmed
up. If the jets have not been adjusted, a rough
adjustment can be first carried out by screwing
the adjuster nuts to their upper position and
then screwing them down again one complete
turn.
2.
Loosen one of the connections (9, Fig. 4) on
the shaft between the carburetors. Make sure
that the jets on both the carburetors are pres-
sing against the adjuster nuts and that the
screw (4) for rapid idling is not in contact with
the cam-shaped plate on each carburetor.
Fig. 20. Measuring air flow for identical settings
on both carburetors.
1. Vacuum-meter
3. Adjust both throttles to the same position by
screwing out the throttle adjuster screws (3 and
7) and then screwing them in again until con-
tact with the stop projections is just made.
Then screw down each screw exactly one turn.
Make sure that the throttles work freely and
i ndependently.
4. Start the engine. Check. that the throttles are
open to the same extent in both carburetors by
fitting a special vacuum-meter to each air
cleaner contact surface. See Fig. 20. Adjust
the idling screws until the meter reading on
both carburetors is exactly the same.
5. Adjust the jets by turning the adjuster nuts so
that the idling speed is as high as possible
with unchanged throttle opening. Adjust the
carburetors one at a time. First screw the
adjuster nuts (1, Fig. 19) upwards (leaner
mixture) until the engine runs unevenly and then
i
n the opposite direction until the engine runs
perfectly smoothly. If the idling speed is too
high it can be decreased by unscrewing the
i dling screws on the throttle shaft levers. Then
check again as specified above that the air
i
ntake is equal on both carburetors.

Fig. 21. Adjusting the throttle setting.
û. Check that the fuel-air mixture is correct on
both carburetors. First lift the piston on one
of the carburetors slightly by means of the pin
beside the air intake. Then release the pin and
carry out the same procedure on the other
carburetor.
The degree of uneven running on the engine
should be the same in both cases.
I f the engine stalls when the piston on one of
the carburetors is lifted, this usually means
that the mixture on the other carburetor is too
l ean. The jet adjuster nut on the carburetor in
question should be screwed carefully down-
wards to remedy this.
7.
Connect the carburetors together by tightening
the couplings on the shaft. Check that air flow
i s equal on both carburetors. See point 4.
Adjust idling speed to 500-700 r.p.m. by using
the idling adjuster screws. Adjust the rapid
i dling screws. This is done by screwing each
screw until it is in contact with the cam plate
and then screwing it back until a certain clear-
ance is obtained.
Rapid idling and choke control
mechanism
When the choke control is completely pushed in,
the clearance between the adjuster screw (4,
Fig. 4) and the cam plate should correspond to
' /2 to 1 turn.
The clamp on the end of the choke cable should
be attached so that the jets begin to go down
when the choke button on the instrument panel
has been pulled out about
1
/2" (rapid idling move-
ment). Increased resistance will be felt on the
choke button when the jets begin to move down-
wards.
When the choke control button is pulled out as
far as it will go, the long lever ends should be
l i fted so far that the jets are completely lowered,
i. e. the levers should contact the stops in the
li nks. Make sure that both levers are influenced
to the same extent through the curved cable so
that both jets start to move downwards at the
same time.
Throttle setting
The position of the accelerator pedal should be
adjusted so that there is a clearance of 0.060"
(1.5 mm) between the stop arm and full-throttle
stop when the accelerator pedal is fully depressed.
This will give the pedal the correct height above
the floor and will also unload the control to a
certain extent.
When adjusting, loosen the coupling (4, Fig. 21),
place a weight on the pedal so that it is pressed
down fully, adjust the clearance and then tighten
the coupling.
N.B. The clearance must not exceed 0.080" (2 mm)
as this will reduce the output. (On early production
there is a lever in front of the carburetor instead
of the coupling (4).
The shaft between the carburetors is fitted so that
the end float is distributed equally at both ends.
I n
cases where the coupling behind the rear
carburetor is in the form of a ridged spring, ensure
that there is clearance between the shaft ends
before tightening.
Air cleaners
The air cleaners with wire wool should be dis-
assembled for cleaning after every 3000 miles.
Clean the filters in clean kerosene and blow then
dry with compressed air. Then soak them in en-
gine oil, let the excess oil run off and re-assemble
them.
Air cleaners with paper cartridges must not be
washed or oiled in.
They should be replaced after every 12,500 miles.
I f the vehicle is used in very dusty or contaminated
1. Feeler gauge, 1.5 mm 3. Lever
2. Full throttle stop 4. Coupling

P
air, they can also be cleaned by carefully blowing
through with
compressed air after every 3000
miles. Blow from the inside out but do not hold
the compressed air nozzle too near.
Make sure that the gaskets are fitted correctly
when re-assembling. The ventilation holes (3, Fig.
11 and 2, Fig. 6) must not, under any circum-
Apart from the points shown below we refer you
to the fault tracing table in the Service Manual
for PV Part 1, B 16 A Engine where this applies.
Before the carburetors are examined in detail, ele-
mentary precautions such as checking that the
Blocked oil filter element.
Faulty valve in oil filter.
CAUSE
Pistons chafing in the carburetors. The pistons are
not going down until they meet the bridge.
I ncorrectly centred jet hampering fuel needle
movement.
The cold starting device is not taking the jet
down to its lowest position.
Uneven
No oil in the carburetor damping devices, the
fuel mixture obtained when the accelerator pedal
i s rapidly depressed being too lean.
Excessively lean fuel-air mixture.
Poor synchronization of carburetors.
2 14
FAULT TRACING
FAULT
stances, be blocked since this can prevent the
carburetor in question from operating correctly.
Fuel
Since this engine has a comparatively high com-
pression ratio, fuel with an octane rating of 93
(Research) should be used.
fuel is reaching the carburetors, that the spark
plugs are working correctly and are receiving
electric current, that all the controls are func-
tioning properly, etc., should be carried out.
REMEDY
Low oil pressure
Replace oil filter element.
Check valve and replace if necessary.
The engine will not idle properly or is difficult to start
Check the movement of the pistons with the aid
of the pin on the air intake. Dismantle and clean
the pistons if required.
Centre the jet.
Adjust the controls and cable attachments in the
carburetor levers. See under the heading "Rapid
i dling and choke control mechanism".
acceleration
Top-up with SAE 20 oil in the damping cylinders.
Adjust the vertical setting of the jet. See under
the heading "Idling settings and coupling of car-
buretors".
Check the position of the fuel needle. See
"Replacement of fuel needle".
Connect together the carburetors when the pass-
age of air through each of them is equal. See
"Idling adjustment and coupling together of car-
buretors".

Excessively high fuel consumption
I ncorrectly fitted fuel needle.
Jet not being properly pressed up against the
adjuster nut, this resulting in excessively rich
fuel mixture.
Driving habits in many cases. Repeated fierce
acceleration and braking.
Adjust the fitting. See "Replacement of fuel
needle". Adjust the vertical position of the jet.
See under the heading "Idling adjustment and
coupling of carburetors".
Check or replace lever spring. Centralize jet.
Lower jet and smear exposed part with oil.
More sensible driving habits.
Leakage from the lower part of the jet
Replace the seal rings.
Seal rings damaged.
The cold starting device functions stiffly
Lower the jet and lubricate the exposed portion.
Centre sleeves, see "Centralizing the jet".
Chafing jet.
Jet sleeves badly centred.
TOOLS
(
Only carburetor tools. See also Service Manual for B 16 A).
1 Wrench for adjuster nut.
SVO 2324 Gauge for float level.
SVO 2369
Centralizing tool for upper and lower
jet sleeves.