1977 DATSUN PICK-UP transmission

Engine
Tune

up

SERVICE
DATA
AND

SPECIFICATIONS

Ignition
timing
and

idling

Manual
transmission

Automatic
transmission

in
D

position

Valve

clearance

Cold
Intake

Exhaust

Intake

Exhaust
Hot

Belt
tension

Fan

Air

pump

Air

coo

compressor

Pressure

Compression
pressure
at
350

rpm

Standard

Minimum

Radiator

cap
relief

pressure

Cooling
system

Leakage
testing
pressure

Battery
specific

gravity
at
200C
680F

Distribu
tor

Point

gap

Air

gap

Dwell

angle

Condenser

capacity

Condenser
insulation

resistance

Spark
plug

Gap
degree
rpm
120
B
T
D

C
j750
Non
Calif

models

100

B
T
D

C
j750
California
models

degree
rpm
l20B

T
D

C
j650

mm
in

mm
in

mm
in

mm
in
0
20
0
008

0
25

0
010

0
25
0
010

0
30
0
012

mm
in

mm
in

mm
in

kg

lb
8
to
12
0
315
to
0
472

8to
12
0
315

to
0
472

8

to
12
0
315
to

0
472

10
22
is

applied

kg
cm2

psi

kg
em2

psi

kg
em
2

psi
12
0

171

9
0
128

0
9

13

kg
cm2

Psi
1
6
23

1

26

mm
in

mm
in

degree

IF

Mil
0
45
to
0
55
0

018
to
0
022

0
2
to
0
4
0

008
to
0
016

490
to
550

0
20
to
0
24

5

mm

in
0
8
to
0
9
0
031
to
0
035

Breaker

points
type

1

0
to
1
1
0
039

to
0
043

Transistor
ignition
type

Checking
CO

percent
at

idling
speed
No
air

Manual
transmission
model

rpm

Automatic
transmission
model

rpm

Adjustment
of

operating
pressure
of
B

C
D
D

B
C
D
D

set

pressure

Manual
transmission

Automatic

transmission
2
1

1
750

2
1
1
650

mmHg
in

Hg

mmHg
in
Hg
510
to
550
20
1

to
21
7

490
to
530
19
3
to
20
9

ET
25

Engine
Mechanical

GENERAL
DESCRIPTION

MODEL

L20B
ENGINE

CYLINDER
BLOCK

CRANKSHAFT

PISTON
AND
CONNECTING
ROD

CYLINDER
HEAD
CONTENTS

EM
2

EM
3

EM
3

EM
3

EM
3
CAMSHAFT

VALVE
MECHANISM

CAMSHAFT
DRIVE

MANIFOLDS

out
smooth

dependable

power

The

cylinder
block
is
cast
as
a

single

unit

and

featllres
deep
skirting
This

engine
is

equipped
with
a

single
2

barrel
downdraft
carburetor
that
in

corporates
a

special
device
to
control

emissions
MODEL
L20B

ENGINE

The
L20B

engine
features
O
H
C

valves

wedge
shaped
combustion

chamber
aluminum
head
and
a

fully

balanced
5

bearing
crankshaft
to
turn

Main

specifications

Oisplacemen
t
cc

cu
in

Bore
x
stroke

mm
in

Compression
ratio

Ignition

timing

Degree
B

T
O
C

rpm
MIT

AlT

MIT
Manual
Transmission
EM535

Fig
EM
Cross
sectional
view

L20B

1

952
1191

85

X
86

3
35
x
3
39

8
5

12
750

Non
California

model

10
750

California

model

12
650
in
0
position

AIT
Automatic
Transmission

EM

2
EM
3

EM
3

EM
3

EM
3

CYLINDER
BLOCK

The

cylinder
block
a
mono
block

special

casting
structure

employs
a

five
bearing

support

system
for

quiet

ness

and

higher
durability

The

cylinder
bores
are
surrounded

by
cooling

jackets
and
machined
di

rectly
in
the
block
The
oil

ways
in
the

block

are
arranged
so
that
the

full
flow

oil
filter
is

directly
attached
to
the

right
hand
side
of
the
block

EM536

Fig
EM

2
Cylinder
block

CRANKSHAFT

The
crankshaft
is

a

special
steel

forging
Fully
balanced
it
turns
out

smooth

dependable
power
at

high

speed

The
L20B

engine
uses

eight
balance

weights

Main

bearings
are
lubricated

by
oil

pumped
through
the
main
oil

gallery

and
the
oil
holes
which
run
in

parallel

with

cylinder
bores
There

are

oilways

drilled
in

the
crankshaft
for
the
lubri

cating
oil
The
center
main

bearing
is

equipped
with
thrust
washers

to
take

up
end

thrust
of
the
crankshaft

r

I

I

PRELIMINARY
CLEANING
AND

INSPECTION

DISASSEMBL
Y

PRELIMINARY

CLEANING
AND

INSt

ECTION

Before

disassembling

engine
note

the

following

I
Fuel

oil
or
water

may
leak

past

cylinder
head
and
block
Prior
to

disassembling
check

cylinder
head

1
1ltermal
vacuum
valve

2
Check

valve

3
Altitude

compensator

in

air
cleaner

4
Air

gallery
pipe

S

Auto
choke

6
Automatic

temperature

control
air

cleaner

7
Anti
8ackfire
valve
A
B

valve

8
Boost
Controlled

Deceleration

Device
Bee
D
D

9
P
c
v

valve

to
Air
relief
valve

11
E

G
R

control
valve

12
B
C
D
D

control
valve
and

solenoid
valve

13

Emergency
air

relief
valve

14
Air

pump
air
cleaner

IS
Carbon
canister

16
Air
control

valve

11
Air

pump
Engine
Mechanical

ENGINE

DISASSEMBLY

CONTENTS

EM
4

EM
4
PISTONS
AND
CONNECTING
RODS

CYLINDER

HE
AD
EM
7

EM
7

front
chain

cover
oil

pan
and
oil

filter

gaskets
lInd
crankshaft
and
water

pump
seals
for

signs
of

leakage
past

their

gasketed
surfaces

2
Check
carburetor
and

fuel

pump

for
condition
fuel
hoses
for

deteriora

tion
cracks

or

leakage
of
fuel

past

their

jointed
or
connected

surfaces

Fig
EM

0
Emiuion
control
devic
s

California
mod
18
E
T366

3
Remove

carburetor
air

cleaner

Remove
fresh

air
duct

Disconnect
hot
air
duct
from

air

cleaner

Disconnect
air

cleaner
to
air

pump

hose
at
air

cleaner

Disconnect
air

cleanef
to
rocker

cover

hose
at
rocker
cover

Disconnect

air
cIeaner

to
air

con

trol

valve
hose
at
air

cleaner
Cali

fornia

models

only
Disconnect
air

cleaner
to
A

B
valve

hose
at
air

cleaner

Disconnect
air

cleaner
to

related

part
vacuum
hoses
at
air

cleaner

Loosen
air

cleaner
band
bolt
and

remove
carburetor
air

cleaner
as

sembly
from

carburetor

4

Plug
up
carburetor
air

horn

to

prevent
entry
of

foreign
matter

5

Remove

alternator
drive

belt

alternator
and

alternator
bracket

EM
4
6

Remove
air

pump
drive

belt
cool

er

compressor
and
idler

pulley
if

so

equipped

7
Remove
starter
motor
from
trans

mission

8

Visually

inspect
cylinder
head

cylinder
block
rocker
C
Ner

front

chain
cover
oil

pan
and
all
other
outer

parts
for
oil
water
and
fuel
leaks

breakage
or

missing
parts
such

as
bolts

and
nuts

9

Check

piping
and
electrical
cir

cuits
for
deterioration

breakage
fit

tings
discontinuity
or
insulation

DISASSEMBLY

To

remove

engine
from
vehicle

refer
to

the
instructions
under
the

Engine
Removal

and
Installation

ER
section

I

Remove
transmission
from

en

gine

2
Remove

clutch

assembly
from

flywheeL

3

Thoroughly
drain

engine
oil
and

coolan
t

by

removing
drain

plugs

Store

engine
oil
and

coolant
if

they

are

to
be

used

again

4
Place

engine
assembly
on

engine

stand

I

Remove

cooling
fan

2

Remove

right
engine

mounting

bracket

3

Remove
oil
filter
with
Oil

Filter

Wrench
STI9320000

4

Remove
oil

pressure
swi

tch

5

Install

engine
attachment
to

cylinder
block

utilizing
bolt

holes
in

alternator

bracket
and

water
drain

hole

6
Set

engine
on
stand

Engine
Attachment

ST05260001

Engine
Stand

ST050I

SOOO

Engine
Mechanical

SERVICE
DATA
AND
SPECIFICATIONS

GENERAL
SPECIFICATIONS

Engine
model
L20B

Cylinder
arrangement

Displacemen
t

Bore
and
stroke
4
in

line

cc
co
in

mm
in
1

952

J
19
1

85
x

86
3

35
x
3
39

O
H

C

I

3
4
2
Valve

arrangement

Firing
order

Engine
idle
rpm

Manual
transmission

Automatic
transmission
in
D

range
750

650

8
5

Compression
ratio

Oil

pressure
Warm
at
2

000

rpm

kg
cm2

psi
3
5
to
4
0
50

to
57

SPECIFICATIONS

a
Valve
mechanism

Valve

clearance
Warm

Intake

Exhaust

Valve
clearance
Cold

Intake

Exhaust

Valve
head
diameter

Intake

Exhaust

Valve
stem
diameter

Intake

Exhaust

Valve
length

Intake

Exhaust

Valve
lift

Intake
and
exhaust
mm
in

0
25
0
010

0
30
0
012

mmOn

0
20
0
008

0
25
0
010

mm
in

42
0
to
42
2
1
654

to
1

661

35

0
to
35
2
1

378
to
1
386

mm
in

7

965
to
7
980
0
3136
to

0
3142

7
945
to
7
960
0
3128
to

0
3134

mmOn

114
9
to
115
2
4
524
to
4
535

115
7
to
116
0
4
555
to
4

567

mmOn

Valve

spring
out

of

square
mm
in
10
5
0
413

less
than
1

6
0
063

Valve

spring
free

length
mm
in

Intake
and
exhaust
Outer

Inner
49
98
1
968

44

85
J
766

EM
27

Conventional

COUplin9

WATER
PUMP
SPEED

F

Z

Tern

coupling

WATER
PUMP

SPEED

C0029

Fig
CO
6
Characteristic

of

Tern
coupling

INSPECTION

Check
Tem

coupling
for
oil

leakage

or
bend
of
bimetal

If
the
above

symptoms
are
found

replace
it
with

a
new
one
as
an

assembly

THERMOSTAT

A
wax

pellet
type
thermostat
is

mounted
in
the
thermostat

housing
at

the

cylinder
head
water
outlet

The
function
of
the
thermostat
is

to
control
the

flow
of
coolant
facili

tating
fast

engine
warm

up
and

regu

lating
coolant

temperature
The
ther

mostat
is

designed
to

open
and
close
at

predetermined
temperatures
and
if

not

operating
properly
should
be

re

moved
and
tested
as
described
below

REMOVAL
AND

INSTALLATION

I

Drain
coolant

partially

2
Disconnect

upper
radiator
hose
at

water
outlet

3

Remove
bolts

and
remove
water

outlet

gasket
and
thermostat
from

thermostat
housing

Fig
CO
7

Removing
therm06t
t
Cooling
System

4

After
checking
thermostat
re

install
with

a
new

housing
gasket
in

place

5
Reinstall
water

outlet

6

Replenish
coolant
and
check
for

leaks

INSPECTION

A

sticking
thermostat
will

prevent

the

cooling
system
from

functioning

properly
If
the
thermostat
sticks
in

the

open
position
the

engine
warms

up
very
slowly
If
the
thermostat

sticks
in

the
closed

position
over

heating
will
result
Therefore
the
ther
mostat
should
be

inspected
to

make

sure
that
it
is
in

good
condition

1
Measure
coolant
temperature

when
thermostat
valve
starts
to

open

2
Measure
the
maximum
lift

of

thermostat
valve

Fig
CO
S

Impecting
therm06t
t

Temperate
Frigid
Tropical

type

type
iype

Valve

opening

80
5
to
83
5
86
5
to
89
5
75

to
78

temperature

177
to
183
187
to
193

167
to
172

oC
OF

Maximum

valve
lift
8
95
8
1
00
8
90

mm
oC

in
F
0
31
203

0
31
212
0
31

194

If
thermostat
does
not

operate
at

the
above

specified

temperature
it

must
be

replaced
because
it
cannot
be

repaired

RADIATOR

The
radiator
is

a
conventional
down

flow

type
having

top
and

bottom

tanks
to

distribute
the
coolant
flow

uniformly
through
the
vertical
tube
of

radiator
core

The

radiator
filler

cap
is

designed
to

maintain
a

pre
set

pressure
0
9

kg
cm2
13

psi
above

atmospheric

pressure

The
relief
valve

consisting
of

a

blow
off

valve
and
a

vacuum
valve

helps
to

prevent
the
coolant
from

boiling
by
giving

pressure
to
it
How

ever
when

the

pressure
is
reduced

below

atmospheric

pressure
the

vacu

um
valve
allows
air

to
re
enter

the

radiator

preventing
the
formation
of
a

vacuum
in
the

cooling
system

CO
5
On
models

equipped
with
auto

matic
transmission

the
oil
cooler
is

combined
with
the

radiator
to
cool

transmission
fluid

REMOVAL
AND

INSTALLATION

Drain
coolant
into
a
clean
con

tainer

2

Disconnect
radiator

upper
and

lower
hoses
On
models
with
auto

matic
transmissions
disconnect
cooler

inlet
and
outlet
lines
from
radiator

3

Remove
fan
shroud
retaining

bolts
and

remove
fan
shroud

4

Remove
front

grille

5

Remove
radiator
retaining
bolts

and
then

remove
radiator

upward

6
Install
radiator
in
the
reverse
se

quence
of
removal
Note
the
fol

lowing

I
Insert
hoses
in

their

positions

until

they
bottom

2
Ensure
that
arrow
marks
on

hoses
are

clearly
visible
from

upper

r

direction
when
hoses
are

assembled

3
Ensure

that
clearance
between

radiator

hose
and

any
adjacent
parts
is

30
mm
I
181
in
minimum

On
mod

els

equipped
with
air

conditions
a

minimum
clearance
of
18

mm
0
709

in
should

exist
between

compressor

and
hose

4
Ensure

that
clearance
between

shroud
and
fan
is

even
at

any
place

Note
Be

careful
not
to

damage
radia

tor
fins
and

core
tube
when
in

stalling

INSPECTION

Radiator

cap
should
be

checked
for

working
pressure
at

regular
tune

up

intervals
First

check
rubber
seal
on

cap
for

tears
cracks
or
deterioration
Cooling
System

after

cleaning
it
Then

install
radiator

cap
on
a

tester
If

cap
does
not

hold
or

will

not
release
at
the

specified
pres

sure

replace
cap

Fig
CO
9

Telting
radiator

cap

Also

inspect
radiator
for

leakage

using
cap
tester

and

applying
a

pres

sure

of
1

6

kg
cm
22
8

psi
If
a

leakage
is

detected

repair
or

replace
radiator

Fig
CO

IO

Testing
cooling
6ystem

pUS
ure

SERVICE

DATA
AND
SPECIFICATIONS

Thermostat

Valve

opening
temperature
oC
F

Maximum
valve

lift
mm
oC

inj
F

Radia
tor

Type

Manual
transmission

Automatic

transmission

Cap
relief

pressure

Cooling
system

Leakage
testing
pressure

Capacity

Manual
transmission

Automatic
transmission

Fan

Number
of
blades
x
outer
diameter

Without
air

conditioner
mm

in

With
air

conditioner
mm
in
kg
em

psi

kg
em

psi

liters
US

qt
Imp

qt

liters
US

qt
Imp
qt

CO
6
Temperate

Frigid
type
Tropical
type

type

80
5

to
83
5
86
5
to
89
5
75
to

78

177
to
183

187
to
193

167
to
172

8
95

8
100
8
90

0
31
203
0
31
212
0
31

194

Corrugated
fin

type

Corrugated
fin

type
equipped
with

oil
cooler

0
9

1
3

1
6
22
8

with

heater

8

0
8
Ii
7

7
8
8
Y

6
J
i
without
heater

74
7J
i6

1i

7
2

7
X
6

X

7
x

380

15

8
x

380

15

FLOAT
SYSTEM

There
IS

only
one

float
chamber

while
two
l

arburetor

systems
primary

Jnd

st
l

ondary
are

provided

Fuel
fed
from
the
fuel

pump
flows

through
the
filler
and
needle

valve
into

the
flo
t
chamber
A

constant
fuel

level

is
maintained

by
the
float
and

needle
valve

Because
of

the
inner
air

vent

type

of

the
float
chamber
ventilation
the

fuel

consumption
will
not

be
in

fluenced

by
some
dirt
accumulated
in

the
air

deaner

The
needle
valve

includes

special

hard
steel
ball

and
will
not

wear
for
all

its

considerably

long
use
Besides
the

inserrion

of
a

spring
wiU

prevent
the

flooding
at

rough
road

running

BOOST

CONTROLLED

DECELERATION
DEVICE

B
C
D
D

A

Boost
Controlled
Deceleration

Device
B

C
D

D
serves
to

reduce
the

hydrocarbons

He
emitted
from
en

gine
during
coasting

The

high
manifold
vacuum

during

coasting

prevents
the
mixture

from

complete
combustion

because
of
the

reduced
amount
of
mixture

per
cyl

inder

per
rotation

of

engine
with
the

result
that

a

large
amount
of

hydrocar

bons
is

emitted
into
tile

atmosphere

The
B

C
D
D
has
been

designed
to

correct

this

problem

It

opern
tes

as
follows

when
the

manifold

vacuum
exceeds
a

pre
Engine
Fuel

determined

value
the

B
C
D
D
intro

duces

an
additional
mixture

of

opti

mum
mixture
ratio
and

quantity
into

the

manifold

by

opening
a

separate

mixture

passage
in
the

carburetor

Complete
combustion

of
fuel
is
assist

ed

by
this
additional
mixture

and
the

amount

of
H
C

contained
in

exhaust

gases
is

dramatically
reduced

During
the

transition

period
from

coasting
to

idling
the
transmission

produces
a

signal
which
turns
on
the

vacuum
control

solenoid
valve
As
this

takes

place
the
valve
is

lifted
off
its

seat

opening
the

vacuum
chamber
to

the

atmosphere
The
mixture

control

valve
is
then

closed

returning
the

engine
to
the

predetermined
idling

speed

On
manual

transmission
models

this

system
consists

of
B
C
D
D

vacuo

urn
control

solenoid
valve

speed
de

tecting
switch
and

amplifier

On
automatic

transmission

models

it
consists

of
B
C
D
D

vacuum
con

trol

solenoid
valve

and

inhibitor

switch

B
C
D
D

operation

Diaphragm
I

Qj
monitors
the

mani

fold

vacuum
and

when
the

vacuum

exceeds
a

pre
fetermined
value
acts
so

as

to

open
the

vacuum
control
valve

@
This
causes

the
manifold

vacu
urn

to
be

introduced
into
the

second

vacuum
chamber
and

actuates
dia

phragm
ll@

When

diaphrngm
II

operates
the

mixture

control
valve

@
opens
the

passage
and
introduces
the
additional

mixture
into

the
manifold

EF

18
The
amount
of

the
mixture

is
con

trolled

by
the

servo
action

of
the

mixture
control

valve

CID
and

vacuum

control

valve

@
so

that

the
manifold

vacuum

may
be

kept
at
the

pre

determined

value

The
amount

of
mixture

depends

mainly

upon
the

coasting
air
bleed

II@
while
the
mixture
ratio

is
deter

mined

by
the

coasting
jet

@
and

coasting
air
bleed

@
See

Figure

EF
31

Vacuum

control
solenoid

valve

operation

Manual

transmission
models

The

vacuum
control

solenoid
valve

is

con
troDed

by
a

speed

detecting

switch
that
is

actuated

by
the

speed

ometer
needle

As
the
vehicle

speed
falls

below
10

MPH
this
switch
is
activated

pro

ducing
a

signal
This

signal
actuates
the

amplifier
to

open
the
vacuum
control

solenoid
valve

Automatic

transmission
models

When
the

shift
lever
is
in
N

or

P

position
the
inhibitor
switch

mounted
on
the
transmission

turns
on

to

open
the
vacuum

control
solenoid

valve

I
Air

jet

2

Diaphragm
II

3
Mixture
control
valve

4

Coasting
air

bleed
II

5
Mixture
air

passage

6

Secondary
baHel

7
Intake
manifold

8
Boost

passage

9
Vacuum
control
solenoid

valve

10
Vacuum
control
valve

II

Diaphragm
I
Engine
Fuel

12

Secondary
main

jet

13

Coasting
jet

14

Coasting
air
bleed
I

15
Inhibitor
switch
N

P

ON
for
automatic

transmission

16

Amplifier

1
7

Speed
de

tecting
swi
tch
below

10
M
P
H
ON

for
manual

transmission

1

W
j

I

t

i
J

l

J
18

Ignition
switch
CID

1
1

fI3
6

@
I

r
101

@
i

r

@

JJ

Note
Broken
line

applies
only
to
Automatic
Transmission

I

Ignition
switch

2

Amplifier

3

Speed
detecting
switch
below

10
M
P

H
ON
for
manual

transmission

4
Inhibitor
switch
N
p

ON
for
automatic

transmission

5
Solenoid
valve

6
Vacuum
control
valve

7
Altitude

corrector

LlJ

I

I

l

f

L8
J

l
EF231

Fig
EF
31
Schematic

drawing
of
B
C
D
D
Non

California
models

1

J
ru

I

r

lJ

i7

I
To
intake

manifold

To
air

cleaner

E
F235

Note
Broken
line

applies
only
to
Automatic
Transmission

Fig
EF
32
Schematic
drawing
of
RC
D
D

California
models

EF
19