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T 1i
t
T
11
10
9
8
7
Fig
. 2·78.
By-pass
va lve
- -
T
6
VO LVO
103635
1.
Gaskel
7.
Screw for
cover
2.
Housing
8.
Cover
3. Gaskel
9.
Rubber
r
in
g
4.
Diap hragm
10
.
Ad
ju
sl
ing
screw
5.
Gaskel
11.
Spr
i
ng
6. Sc rew for by-pass
va
lve
p
instic
cover and press ing
-
i n
the valve
(3,
Fig
.
2-27).
Th
is
shou,ld
move under
very
light
pressure
and re
turn
to its
position
w~thout
jamming.
Th is
appHes
at
a
temperature
above
80°
F. The
valve
sta'rts
open
ing
at
70°-77°
F.
P.res-
s ingthe vallve
inwa-rd
s
deteriorate'
s the
quallity
of t he
idl
e.
If .the
valve
ha
s
a tendency to be
stiff
in operation
or if the compensator
is
incorrectly
ad
ju
sted
,
the
lal
t ter shoul,d
be rep laced co
mpl
ete.
See
und
er
"Replaoing
the
temperature compen-
sator".
For
adjusting
slacken
o ne
of the
cross-s lotted
screws
(8),
for the bi-metnl
sp
ring
and center
the
valve so
that
il
r s
function
wtll be
as above.
If
necessary
aodjust as follows:
A
70-77°
F
the
va·lve
should ju
st start
to open.
In
other
wo rds,
the
valve should be
lo
ose
in
its sea
t
at this tempeorature.
When
checking the setting, remove the
tempera-
ture compensator
from the carburett-or and
store
it
at
a temperature
of
70-77°
F
until it has reached
this
tempemture.
Adjust
with the nut
(9)
for
the
bi-metal spring.
By-pass valve (front
carburettor)
4.
With faulty function of the bY-lpas·s vall ve, or if
,
t he
engine does not reduce speed at .j.dle (hrst
check
that ,the
throttle controi
is correctly
adjusted)
or
if
,
t he valve does not open, then adjust as follows:
A
Engine does
not
reduce speed at
idle:
Turn the adjusting screw
(S,
Fig.
2-S0
to
the
left
until
rthe
engine reduces idling speed.
Check the funct ion by running the engine briefly
up to ab out
2000
'r.p,m.
The
eng ine shou ld then
return t
o
idli
ng speed. (Note t hat t he eng ine will
re
turn to
,
i dl
e
som ewhat
slowe
r
than
is t
he
case
with a carburettor
withoul
t a by
-pa'
s s valve.) When
conect funation
,is
obta ined (that
is,
even the
fundion
accordin
g to B), turn
the
screw a further
1/2
turn
to <the ·Ieft.
B
The va lve does
no
~-
open:
Norma
lly
the a ir va lve of the front carburettor
should go down
.
t o
the
bridge a
little
arter that
of -the
rear
ca,rburettor on racing the engine speed.
Turn
the
adjusting screw to the right untj.l normal
funct ion is obtained.
If
this not possible, replace
the
,by ~pass
va lve complef.e, see under "Replacing
the
by-pass
valve".
N.B.
When ad
justing,
do not press the adjusting
screw
inwards
since .the rubber ,ring
(9,
Fig
.
2-78)
seal ing between the screw and cover can drop out
of
posi'
t ion. Check for air leakag·e by
e.g.
placing
a f inger over the rubber r ing hol'e.
REMOV ING THE CARBURETTORS
Remove
the va,lve controi for the hot-start valve and
the air cleaner,
Remove rthe
link
rod ba
ll
joints
from
,the
carburettors. T a k'e off the
fuel
hoses, vacuum hose
and
choke
wire.
Remove
,
t h
e
nuts
for
the carburettors and
ta ke off t he
cdrburettors,
Remo ve
the
profeation
p lates
and
ga
skets,
Ma sk
over t
he intak
e
holes with tape.
FITTING THE
CAR
BURETTO RS
Clean
thega sket
surface.
Fit
the tprotection plates,
new
gaskets and
t hen
the
carb uret:tors.
Conn'
e d
rthe
ball
jo
ints,
fuel hoses, vacuum
hose a
nd
choke
wire.
Make
sure
that
the choke
,controi
on
the
dashboard
is
pushed
in
.
Then
secu-
re
th
e
pul·1
wire
in the alamping
screw
of the
rap id
idl
e
cam.
A~terthis
dip on the
outer sleeve of the pull
wire.
Fit
the air
cl
ea
ner
and
conned the hose for the
crankcase
ventila,
t i·on.
Fit
the
valve
aontrol
for the
hot-start
valve.
Adjust
the carbu,remtors,
see
under
"Sertting the carburettors".
Checking the secondary throttles
Check to
make sure
<that
the secondary
throt,t.les are
centered and 'can be
turned
without jamming.
Check
<the
location
("A",
Fig.
2-79
of levers. W ,hen the
se
-
condary
throttle
is dosed, the distanoe "A" between
the
leve,r
pin and
the
'int
ake manifold flange
should
be
.7-4,3
mm
(0.11-0.17").
2:
3S
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