1973 DATSUN B110 Service Repair Manual

ENGINE

6

f

I

Filter

to

Primary
main
nozzk
18

Secondary
throttle
valve

2
Needle
valve
11

Primary
main
air
bleed

19

Primal
throttle
valve

3

Secondary
slow

jet
12

Primary
slow
air
bleed
20
Idle
nozzle

4

Secondary
slow
air
bleed
13

Primary
slow

jet
2t

By
pass
hole

5

Secondary
main
air
bleed
14
Float
22

Primary
main

jet

6

Secondary
main
nozzle
15

Secondary
emulsion
tube
23

Primary
emulsion
tube

7

Secondary
air

vent

pipe
t6
Secondary
main

jet
24

Power
valve

8
Choke
valve
t7

Auxiliary
alve
25
Level

gauge

9

Primary
air
nt

pipe

Fig
EF
15
Sectional
view

of
model
DCH306
carburetor

bleed
The

gas
mixture
is

injected
into
the
venturi

through
the
main
nozzle

When
the

throttle
valve
is
wide

open
and
the

engine

requires
dense
mixture

gas
the

power
valve

opens

from
where
the
fuel
also
flows
into
the
main

system
Primary
system

Primary
main

system

The
fuel

flowing
out
of
the

passages
at
the

bottom
of

the

float
chamber

passes
through
the

primary
main

jet

and
is
mixed
with

the
air

coming
from
the
main
air

Secondary
side

Primary
side

1

Primary
main
nozzle

2

Primary
main
air
bleed

3
Primary
slow
air
bleed

4

Primary
slow

jet

5
Secondary
throttle
valve
6
Primary
throttle
valve

7
Idle
nozzle

8

By
pass
hole

9
Primary
main

jet

Fig
EF
16

PaTtially
loading

EF
10

FUEl

SYSTEM

Idling
and
slow

system

Passing
through
the
main

jet
the
fuel

passage
is

separated
from
main

line
fuel
flows

through
the

slow

jet
primary
slow
air
bleed
is

ejected
from
the

by
pass

hole
and
idle

nozzle

Accelerating
mechanism

Cj

f

li

Ip

j

1

2

3

4
5
Inlet
valve

6
Outlet
valve

7
Primary
throttle
valve

8

Pump
connecting
rod
Pump
lever

Pump
nozzle

Piston

Piston
return

spring

Fig
EF
17

Accelerating
mechanism

A

mechanical
accelerating

pump
synchronized
with
the

throttle
valve
is
used

When
the
throttle
valve

is
closed
the

piston
rod
is

pushed
up
with
the

linkage
which

pushes
up
the

piston

through
the

piston
return

spring

When
the

piston
comes
down

the
inlet
valve
closes
the

outlet
valve

opens
and
the

fuel
within
the

pump
is

blown
out
from

the

pump
jet
by
the

compressed
piston

return

spring
The

fuel
hits

against
the
side
wall
of
the

small
venturi

becoming
minute

drops
and

compen

sating
trancient

sparseness
of
the

fuel

Power
valve
mechanism

The

power
valve
mechanism
so

called
vacuum
actuated

boost

type
makes
use
of
the
downward

pulling
force

of
the

air
stream
below
the

throttle
valve

When

the
throttle
valve
is

slightly
opened
during
light

load

running
a

high
vacuum
is
created

This
vacuum

pulls
the
vacuum

piston
upward
against

the

spring
leaving
the

power
valve
closed

When
the

vacuum
is

lowered

during
full

load
or

accelerating
running
the

spring
pushes
the
vacuum

piston
downward

opening
the

power
valve
to
furnish

fuel

EF
11
Secondary
system

Secondary
main

system

When
the

primary
throttle
valve
is
wide

open
and
the

engine
produces
high
power
the

secondary
throttle

valve

begins
to

open
by
the

linkage

However
the

auxiliary
Y
J

lve
does

not

open
at
a
slow

speed
due
to
the

counterweight
connected
to
the
valve

shaft

As
the

engine
picks
up

speeds
the

auxiliary
valve

opens

against
the

load
of
the

counterweight
and
the
second

ary
system
starts

operation
for

high
power
operation

The
fuel

flowing
out
of
the

passage
at
the
bottom
of

the
float

chamber

passes
through
the

secondary
main

jet
The
fuel
is
mixed

with
the
air

coming
from
the

main
air

bleed
and
the
mixture
is
blown
into
the

venturi

through
the
main
nozzle

When
the

primary
throttle
valve
is
in
the
full

open

position
the

secondary
throttle
valve
is
also

fully

opened

t

2

3

4
5

Auxiliary
valve

6
Secondary
throttle
valve

7

Primary
throttle
valve

8

Primary
main

jet
Counter
lever

Primary
main
nozzle

Primary
main
air
bleed

Counterweight

Fig
EF
1B
At

full
open
slow

speed

j

1

2

3

4

5

6
Counter

weight
7

Secondary
main
air
bleed
8

Secondary
main
nozzle
9

Counter
lever
10

Primary
main
nozzle
11

Primary
main
air

bleed
Secondary
main
jet

Auxiliary
valve

Secondary
throttle
valve

Primary
throttle
valve

Primary
main

jet

Fig
EF
19
At

full
open
high
speed

ENGINE

Step
system

The
construction
of
this

system
corresponds
to

the

idling
and
slow
system
of
the

primary
system

This

system
aims
at
the

power

filling
up
of
the

gap

when
fuel

supply
is

transferred
from
the

primary

system
to
the

secondary

system
The

step
port
is

located

near
the

auxiliary
valve
in
its

fully
closed

state

Anti

uesetmg

solenoid

Ignition
switch

OFF
ON

I

L
i1

7

I
Anti

dieseling
solenoid

valve

When
the

ignition
key
is
turn

to
OFF

current
will

not
flow

through
the

solenoid
and
the
slow

system
fuel

passage
is

closed
to
shut
down

the

engine
without

dieseling

If
anti

dieseling
solenoid
is
found

defective

replace
the

solenoid
as
an

assembled
llnit

Fuse

Ignition
switch

T
Baitery

717

Fig
EF
20
Schematic

drawing
of
anti

dieseling
solenoid

Removal
and

installation
of
anti
dieseling
solenoid

Removal

Solenoid
is

cemented
at

factory
Use

special
tool

STl9
I

50000
to

remove
a

solenoid

When

this
tool
is

not
effective
use
a

pair
of

pliers
to

loosen

body
out
of

position

Installation

I

Before

installing
a
solenoid
it
is
essential

to
clean
all

threaded

parts
of

carburetor
and
solenoid

Supply

screws
in
holes

and
turn
them
in

two
or
three

pitches

2

First
without

disturbing
the

above

setting
coat

all

exposed
threads
with
adhensive
the
Stud
Lock
of

LOCTlTE
or

equivalent

Then

torque
screws
to
35
to
55

kg
cm
30
to
48

in
lb

using
a

special
tool
STl9150000

After

installing
anti

dieseling
solenoid
leave

the

carburetor

move
than
12
hours
without

operation

3
Mter

replacement
is

over
start

engine
and
check
to

be

sure
that
fuel
is
not

leaking
and
that
anti

dieseling
solenoid
is
in

good
condition
Notes
a
Do
not
allow
adhesive

getting
on
valve

Failure
to
follow
this
caution
would
result
in

improper
valve

performance
or

clogged
fuel

passage

b

In

installing
valve
use
caution
not
to
hold

body
directly
Instead

use
special
tool

tight

ening
nuts

as

required

Float

system

Fuel
fed
from
the

fuel

pump
flows

through
the
filter

and
needle
valve
into
the
float
chamber
A
constant
fuel

level
is
maintained

by
the
float
and

needle
valve

As
ventilation
within
the
float

chamber
is
of
an

air
vent

method

Electric
automatic
choke

An
electric
heater

warms
a

bimetal
interconnected
to

the
choke
valve
and
controls
the

position
of
choke
valve

and
throttle
valve
in
accordance
with
the

elapse
of
time

or

the
warm

up
condition
of

engine

The
construction
and
function
of
each

part
of
this

automatic

choke
are

as
follows
See

Figure
EF
21

EF
12

FUEl

SYSTEM

l

I

@

1J
w

I

I

I

I

1

1
1
t

2

3

4

5

6

7

8

9

10

tt

12
Hi
metal

Heater

Bi
metal

cover

Fast
idle

earn

Bi

metal

Bi

metal

index
mark

Choke

shaft
lever

Choke
valve

Unloader

tang

Vacuum

diaphragm

Throttle
valve

Fast
idle

adjusting
screw
j

@

Fig
EP
21

Construction

of
electric

automatic
choke

Bi

metal
and
heater

Electric
current
flows

through
the
heater

as
the

engine

starts
and
warms
bi

metal
See

Figure
EF
22
The

deflection
of
bi
metal
is
transmitted
to
the

choke
valve

through
the
choke
valve
lever

Ignition
switch
Fuse

Alternator

T

o

o
Auto
choke
relay

Auto

choke
heater

Fig
EF
22
Schematic

drawing
of
electric

automatic
choke
heater

Fast

idle
C3m

The
fast
idle
cam
determines
the

opening
of
throttle

valve

so
as

to
obtain

proper
amount
of
mixture

corresponding
to
the

opening
of
the

choke
valve
which

depends

upon
the
warmed

up
condition
of
the

enigne
Fast
idle

adjusting
screw

This

screw

adjusts
the

opening
of

the
throttle
valve

by

fast
idle

cam

Unloader

When

accelerating
the

car

during
the
warm

up
period

that

is
before
the
choke
valve
does
not

sufficiently

open
this
unloader
makes
the

choke
valve

open
to
a

certain
extent

so
as
to
obtain
an

adequate
air

fuel

mixture

Vacuum

diaphragm

The

moment
when

engine
starts
this

diaphragm
forces

choke
valve

open
to
the

predetermined
extent
so
as

to

provide
necessary
amount
of
air

fuel
mixture

Bi

metaI
index
mark

The
bi

metal
index
mark

is
used
for

setting
the

moment
of
the

bi
metal
which
controls
the

mixing

ratio

required
for

starting
the

engine

EF
13

ENGINE

AD
JUSTMENT

Idling
adjustment

Idle

mixture

adjustment
requires
the

use
of
a
CO

meter
When

preparing
to

adjust
idle
mixture
it
is

essential
to
have
the

meter

thoroughly
warmed
and

calibrated

Warm

up
the

engine
sufficiently

2
Continue

engine
operation
for
one
minute
under

idling
speed

3

Adjust
throttle

adjusting
screw
so
that

engine
speed

is
800

rpm
in
N

position
for

automatic
transmission

4
Check

ignition

timing
if

necessary
adjust
it
to

the

specifications

Ignition
timing
50
800

rpm

5

Adjust
idle

adjusting
screw
so
that
ca

percentage
is

1
5
t
0
5

6

Repeat
the

adjustments
as

described
in

steps
3

and

5

above
so
that
ca

percentage
is
1
5

to
5
at
800

rpm

Cautions
a
On
automatic
transmission

equipped

model
check
must
be
done
in
the
0

position
Be
sure
to

apply
parking
brake
and

to
lock
both
front
and

rear
wheels
with
wheel

chocks

b
Hold
brake

pedal
while

stepping
down

on

accelerator

pedal
Otherwise
car
will
rush
out

dangerously

7
On
automatic
transmission

equipped
model
make

sure
that
the

adjustment
has
been
made

with
the
selector

lever
in
N

position

And
then
check
the

specifications
with

the
lever
in

D

position
Insure
that
CO

percent
and
idle

speed
are
as

follows

Idle

rpm
650

ca

percentage

with

lever
in
D

position
15
to
5

If

necessary
adjust
by

progressively
turning
throttle

adjusting
screw
and
idle

adjusting
screw
until
correct

adjustments
are

made

Notes
a
Do
not

attempt
to
screw
down
the
id
Ie

adjusting
screw

completely
to
avoid

damage
to
the

EF
14
tip
which
will
tend
to
cause
malfunctions

b
After
idle

adjustment
has
been
made
shift
the

lever
to
N
or
p

position
for
automatic

transmission

c

Remove
wheel
chocks
before

starting
the
car

Throttle

adjusting

screw

2
Idle

adjust

ing
crew

3
Idle
limiter

cap

4

Stopp
r

Fig
EF
23
Throttle

adjusting
screw
and
idle

adjusting

screw

Idle
limiter

cap

Do
not
remove
this

idle
limiter

cap
unless

necessary

If
this
unit
is

removed
it
is

necessary
to

fe

adjust
it
at

the
time

of
installation
To

adjust
proceed
as
follows

1
Make
sure
that
the

percentage
of

CO
contents

satisfies
the

specifications

2

Install
idle
limiter

cap
in

position
making
sure
that

the

adjusting
screw

can
further
turn
3

8
rotation
in
the

Ca
RICH
direction

j
j
Carburetor

stopper

o

u

o

i

r
3
8
rotation

0

0

Idle
limiter

cap

0
0

CO
lean

Fig
EF
24

Setting
idle
limite

cap

CD

r
Fuel
level

adjustment

@

@

It
I
Float

2

Float
seat
FUEL
SYSTEM

2

Adjust
bottom
float

position
so
that

clearance
h

between

the
float
seat
and
the
needle
valve

stem
is
1

3
to

1
7

mm
0
0512

to
0
0669

in
when
the

float
is

fully

raised
Bend
the

float

stopper

properly
as

required

l

lH

H

ld

up

@

h
Fast
idle

adjustment

Remove
the
bi
metal
cover

3

I
Float

stopper

4
Needle
valve
2
Place
the

fast
idle

arm
on
the
second

step
of

the
fast

idle
earn
Then

adjust
the
fast

idle

adjusting
screw
in
such

a

way
that
the
clearance
of

the
throttle
valve

shown

at

A

in
the
illustration
will
be

the

specifications
See

Figure
EF
26

Fig
EF
25

Adjsuting
float
level

Turn

down
the
float

chamber
to
allow
the
float

coming
into

contact
with
the
needle
valve
and

measure

H
shown
in

Figure
EF
25
When
the
H
is

approxi

mately
19
0
mm

0
748
in

top
float

position
is

correct

The

top
float

position
can
be

adjusted
by
bending
float

seat

Upon
completion
of
the

adjustment
check
fuel
level

with
the

atta
led
level

gauge
Clearance
of
throttle

Engine
revolution

valve
A

mm
in

rpm

Manual
0
80
to

0
88

transmission
0
0315
to
0

0346
1
750

to
2
050

Automatic
1
07
to

l
l
7

transmission
0
0421

to
0

0461
2

650

to
2

950

Fast
idle
earn

steps

5
C

0
J
t

E

r

L

E
I
I

Ogc
l

0

0

JO
A

Throttle
chamber

Fig
EF
26

Adjusting
fast
idle

EF
15

ENGINE

Vacuum
break

adjustment

I

Completely
close
the
chuke
valve

2
Hold
the
choke
valve

by
stretching
the
rubber
band

between
hoke

shaft
lever
and
the
sta

tionary

part
of

carburetor

3

Grip
the

vacuum
break
stem
with

pliers
and

pull

straight
fully

Vacuum
break
rod

Vacuum
break
stew

Rubber
band
4
Under
this

condition

adjust
the

gap
shown

at
B

in
the

illustration
between
the
choke

valve
and

carbure

tor

body
to
1
140
to
1
260
mm

0
0449
to
0
0496
in
for

manual
transmission
car

and
1

205
to
1
335
mm
0
047

to
0
053
in
for
automatic
transmission

car

by
bending

vacuum
break
rod

I

Fig
EF
27

Adjusting
vacuum
break

Choke
un
loader

adjustment

I

Completely
close
the
choke
valve

2
Hold
the
choke
valve

by
stretching
a
rubber

ring

between
the
choke
shaft
lever
and
the

stationary

part
of

the
carburetor

3

Open
the
throttle
lever

until
it

fully
opens

4

Under
this
condition

adjust
the

clearance
C
in
the
illustration
between
the
choke

valve
and
the
carburetor

body
to
2
01

mm
0
079
in

by
bending
unloader

tongue

See

Figure
EF

28

Note
Make
sure
that
the
throttle
valve

fully
opens
when

the
carburetor
is
mounted
on
the
car
If
the

throttle
valve
fails
to

fully

open
the
unloader

becomes

inoperative
resulting
in

poor
acceleration

after
the

engine
is
started

EF
16

FUEL
SYSTEM

c

Oke
valve

1

Or

Rubber
band

Fig
EF
2B

Adjusting
choke
unloadeT

Hi
metal

setting

Measurement
of
bi
metal
heater

resistance
Install
the

bi
metal
cover
in

place
on

the
carburetor
Make

sure
that

the
resistance

across
the

terminal
and
the
carburetor

body

is
in

the

range
from
8
6

to
9
0

ohms
Measure

the

resistance
without

electric
current

through
the

heater
and

at
about

210e
700F

Note
Use
an
accurate

measuring
instrument
such
as
a

wheatstone

bridge

2
Bi
metal

cover

setting

Position
the
hi

metal
cover
until
the
index

mark
is

aligned
at
the
middle

point
of
the
scale

Note
When
somewhat
over
choked
set
bi
metal

cover

after

turning
it
clockwise

slightly
Fig
EF
29

Setting
hi
metal
cover

EF
17