1977 DATSUN PICK-UP engine

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

Valve

spring
pressured
length

valve

open

Intake
and
exhaust

Outer

Inner

Valve

spring
assembled
height

valve

close

Intake
and
exhaust

Outer

Inner

Valve

guide
length

Intake
and

exhaust

Valve

guide
height
from
head
surface

Valve

guide
inner
diameter

Intake
and
exhaust

Valve

guide
outer
diameter

service

parts

Intake
and
exhaust

Valve

guide
to
stem
clearance

Intake

Exhaust

Valve
seat
width

Intake

Exhaust

Valve
seat

angle

Intake
and
exhaust

Valve

seat
interference
fit

Intake

Exhaust

Valve

guide
interference
fit

b
Camshaft
and

timing
chain

Camshaft
end

play

Camshaft
lobe
ift

Intake
and
exhaust

Camshaft

joumal
diameter

1st

2nd
3rd
and
4th
Engine
Mechanical

mm

kg
in
lb

mm

kg
in
lb

mm
in

mIll
in

mm

in

mm

in

mm
in

mm
in

mm
in

mm
in

rnm
in

rnm
in

mm
in

Camshaft
bend

mm
in

Camshaft

journal
to

bearing
clearance
mm

in

Camshaft

bearing
inner
diameter
rnm
in

1st
2nd
3rd
and

4th
29
5
49
0
1
IM

108

24
5

25
5
0
965

56
2

40
0
21
3
1
575

47
0

35
0
12
3
1
378
27
I

59
0
2
323

10
6
0
417

8

000
to
8
018
0
3150
to
0
3157

12
223
to
12
234

0
4812

to
0
4817

0
020
to

0
053
0

0008
to
0
0021

0
040

to
0
073

0
0016
to
0
0029

1
4

to
1

6
0
0551
to
0
0630

1

8
to
2

2
0
0709
to
0
0866

450

0
081
to
0
113

0
0032
to
0
0044

0
064
to
0
096
0

0025
to
0
0038

0
027
to
0
049
0

0011
to
0

0019

0
08

to
038
0
0032
to
0
0150

7

0
0
276

47
949
to
47
962

1
8877
to
1

8883

0
02
0
0008

0
Q38
to
0
067
0
00
I
5

to
0
0026

48
000
to
48
016

1

8898
to
1
8904

EM

28

Engine
Mechanical

c

Connecting
rod

Center
distance

mm
in

Bearing
thickness
Standard

mm
in

Big
end

play
mm
in

Connecting
rod

bearing
clearance

mm
in

Connecting
rod
bend
or
torsion

per
100
mm
or
2
937
in

mm
in

d
Crankshaft

and
main

bearing

Journal
diameter

Journal

taper
out
of
round

Crankshaft

free
end

play

Wear
limit
of
dittoed

play

Crank

pin
diameter

Crank

pin

taper
out
of

round

Main

bearing
thickness
StJlndard
146
5

748

1
493
to
1

506
0
0588
to

0
0593

0
20
to
0
30

0
008
to

0
012

0
D25
to
0

055
0
0010
to
0
0022

less

than
0
03
0
0012

mm
in

mm
in

mm
in

mm
in

mm
in

mm
in

mm
in
59
942
to
59

955

2
3599
io
2
3604

less

than
0

0
I
0

0004

0
05
to
0
18

0
0020
to
0
0071

0
3

0
0118

49

961
to
49
974
1

9670
to
1
9675

less
than
0
01
0

0004

1

827
to
1

835
0
0719
to

0
0722

0

020
to
0
062
0

0008
to
0

0024

0
12

0
0047

0
05
0

0020
Main

bearing
clearance

mm

in

Wear
limit

of
dittoed
clearance
mm
in

Crankshaft
bend

mm
in

Flywheel
runout

at
clutch

disc
contact
face

mm
in

e
Piston

Pistondiarneter

Service
standard

0

50
0
0197
Oversize

1
00
0

0394
Oversize

Ring
groove
width

Top

Second

Oil

Piston
to
bore
clearance

Piston

pin
hole
off
set

Piston

pin
hole

diameter

f
Piston

pin

Pin
diameter

Pin

length
less
than
0
15
0

0059

mm
in
84
985
to

85
035

3

3459
to
3
3478

85

465
to
85
515

3
3648
to

3
3667

85
965
to
86
015

3
3844
to
3

3864

2
030
to
2

050
0
0799
to
0

0807

2

020
to
2

040
0
0795
to

0
0803

4
015
to
4
040
0
1581
to
0
1591

0
Q25
to
0
045
0
0010
to

0
0018

0
95
to
1

05
0

0374
to
0
0413

21
001
to
21

008
0
8268
to
0

8271
mm
in

mm
in

mm
in

mm
in

mm
in

mm
in

mm
in

20
993
to

20
998

0
8265
to
0

8267

72
25
to
73
00

2
8445
to
2
8740

0
008
to
om
0
0
0003

to
0
0004
mm
in

Piston

pin
to

piston
clearance

mm
in

Interference

fit
of

piston

pin
to

connecting
rod

bushing

mm
in

om
5
to

0
035
0
0006
to
0

00
I
4

EM
29

Engine
Mechanical

g
Piston

ring

Ring
height

Top
and

second

Side
clearance

Top

Second

Ring
gap

Top

Second

Oil
mm
in

mrn
in

mm
in

h
Cylinder
block

Cylinder
bore
inner
diameter
mm
in

Wear
limit
of
dittoed
inner

diameter

Cylinder
bore

taper
and
out
of
round

Difference
in

cylind
bore

Surface
flatness
mm
in

mm
in

mm
in

mm
in

i

Cylinder
head

Surface
flatness

mm
in

TIGHTENING
TORQUE

Cylinder
head

bolts

kg
m
fl
lb

Connecting
rod

big
end

nuts
kg
m
ft
Ib

Flywheel
fixing
bolts

kg
m
ft
Ib

Main

bearing
cap
bolts

kg
m
ft
lb

Camshaft
bracket
bolts

kg
m
ft
lb

Camshaft

sprocket
bolt

kg
m
ft
lb

Oil

pan
bolts

kg
m

ft
1b

Oil

pump
bolts

kg
m
ft
lb

Oil
strainer

bolts
kg
m

ft
lb

Oil

pan
drain

plug
kg
m
ft
lb

Rocker

pivot
lock
nuts

kg
m

ft
Ib

Camshaft

locating
plate
bolts

kg
m
ft
lb

Carburetor
nuts

kg
m

ft
lb

Manifold
bolts

kg
m
ft
lb

Fuel

pump
nuts

kg
m

ft
lb

Crank

pulley
bolt

kg
m
ft
lb

Water

pump
bolts

kg
m
ft
Ib

Front
cover
bolts

kg
m
ft

lb

EM

30
1
977
to
1
990
0

0778
to

0
0783

0
040
to
0
073
0
0016
to

0
0029

0

030
to
0

070
0
0012
to
0

0028

0
25
to

0
40
0
0098
to
0

0157

0

30
to
0

50
0
0118
to

0
0197

0
30
to
0

90
0

0118
to
0
0354

85
000
to
85
050

3
3465

to
3
3484

0
2

0
0079

om
5
0

0006

0
05
0
0020

less
than
0

05
0

0020

less
than
0
05

0
0020

6
5
to
8
5

47
to
61

4
5
to
5
5

33
to
40

14

to
16

101
to
116

4
5
to

5
5
33
to
40

1

8
to
2

0

13
to
15

12
to

16
87
to
116

0
6

to
0
9
4
3
to
6
5

I
J
to
1
5

8
0
to

10
8

0
8
to
1
1
5
8
to
8
0

2
0

to
3
0

14
to
22

5
0
to

6
0

36
to
43

0
6

to
0
9

4
3
to
6
5

0
5
to
1

0
3
6

to
7
2

1
2
to
1
6
8
7

to
11

6

1
2
to
1
8
8
7
to
13

0

12
to

16
87
to
116

0
4
to

0
5
2
9

to
3
6

8
mm
0
315
in

dia

6
mm
0

236
in
dia
1

0
to
1
3
7
2
to

9
4

0
4
to
0
6
2

9
to
4
3

Engine
Mechanical

TROUBLE
DIAGNOSES
AND

CORRECTIONS

Condition

I

Noisy
engine

Knocking
of
crankshaft

and
bearing

Knocking
of

piston

and

connecting
rod

Camshaft

knocking

Timing
chain
noise

Camshaft
and
valve

mechanism

knocking

Water

pump
knocking
Probable
cause

Loose
main

bearing

Seized
bearing

Bent
crankshaft

Uneven
wear

of

journal

Excessive
crankshaft
end

play

Loose
bearing

Seized

bearing

Loose

piston
pin

Loose

piston
in

cylinder

Broken

piston
ring

Improper
connecting
rod

alignment

Loose

bearing

Excessive
axial

play

Rough
gear
teeth

Broken
eam

gear

Improper
chain
tension

Worn
and
or

damaged
chain

Worn

sprocket

Worn
and
or

broken
tension

adjusting

mechanism

Excessive
camshaft
and

bearing
clearance

Improper
valve
clearance

Worn

adjusting
screw

Worn
rocker
face

Loose
valve
stem

i1
1
guide

Weakened
valve

spring

Seized
valve

Improper
shaft
end

play

Broken

impeller

II
Other
mechanical
troubles

Stuck
valve

Improper
valve
clearance

Insufficient
clearance
between
valve
stem

and

guide

Weakened
or

broken
valve

spring

Biting
or

damage
of
valve
stem

Poor

Quality
of
fuel

EM
31
Corrective
action

Replace

Replace

Repair
or

replace

Correct

Replace
cen
ter

bearing

Replace

Replace

Replace
pin
or

bushing

Recondition

cylinder

Replace

Realign

Replace

Replace
bearing
thrust

plate

Repair

Replace

Adjust

Replace

Replace

Replace

Replace

Adjust

Replace

Replace

Replace
guide

Replace

Repair
or

replace

Replace

Replace

Adjust

Clean
stem
or
ream
guide

Replace

Replace
or
clean

Use
ood
fuel

Condition

Seized
valve

seat

Excessively
worn

cylinder
and

piston

Faulty
connecting

rod

Faulty
crankshaft

bearing
Engine
Mechanical

Probable

cause

Improper
valve

clearance

Weakened
valve

spring

Thin
valve
head

edge

Narrow
valve
seat

Overheating

Over

speeding

Stuck
valve

guide

Shortage
of

engine
oil

Dirty

engine
oil

Poor

quality
of
oiL

Overheating

Wrong
assembly
of

piston
with

connecting

rod

Improper
piston

ring
clearance

Broken

piston

ring

Dirty
aii

cleaner

Mixture
too
rich

Engine
over

run

Stuck
choke
valve

Overchoking

Shortage
of

engine
oil

Low
oil

pressure

Poor

quality
of

engine
oil

Rough
surface
of

craokshaft

Clogged
oil

passage

Bearing
worn
or

eccentric

Bearingimproperly
assembled

Loose

bearing

Connecting
rod

alignment
incorrect

Shortage
of

engine
oil

Low

oil

pressure

Poor

quality
of

engine
oil

Craokshaft

journal
worn
or

out
of
round

Clogged
oil

passage
in

crankshaft

Bearing
worn

or
eccentric

Bearing
improperly
assembled

Eccentric

craokshaft

or

bearing

EM
32
Corrective
action

Adjust

Replace

Replace
valve

Reface

Repair
or

replace

Drive
at

proper
speeds

Repair

Add
or

replace
oil

Clean

crankcase

replace
oil
and
oil
niter

element

Use

right
oil

Repair
or

replace

Repair
or

replace

Adjust

Replace

Clean

Adjust

Drive
at

proper
speeds

Clean

and

adjust

Start

correct

way

Add
oiL

Correct

Use

proper
oil

Grind
and

replace

bearing

Clean

Replace

Correct

Replace

Repair
or

replace

Add
or

replace

Correct

Use

proper
oil

Repair

Clean

Replace

Correct

Replace

Engine
Mechanical

SPECIAL
SERVICE
TOOL

No
Tool
number

tool
name
Description

Unit
mm
in

Engine
stand

assembly
This

engine
stand
assembly
is
used
for

disassembling
or

assembling
engine
block

or
differential
carrier

throughout

3600
in

all
directions
ST050lS000

ST050
11000

Engine
stand

ST050

12000

Base
For

use

on
Reference

page
or

Figure
No

All

Fig
EM
II

models

SE184

2
ST0526oo0l
This

engine
attachment
is
installed
to

engine
stand
Ll6

Fig
EM
II

ST0501S000
in

disassembling
or
assembling
engine
Ll8

Engine
attachment

L20B

Q

li

SE185

3
STl
0120000
Special
hollow
set
bolts
are
used
in

tightening
cylinder
heads
All

Fig
EM

18

in

L
series

engines
This
wrench
is
used
to

torque
cylinder
L
series

Cylinder
head
bolt

head
bolts
and
its
head
can
be
inserted
into
the

torque

1
rench

wrench

10
0
39
SE186

4
STl
064000
I
This
tool
is
used

togetller
with
a

torque
wrench
in

tightening
pivot
lock
nut
for
valve
clearance

adjustment

Pivot

adjuster

SE187

EM
33
All
Fig
EM
105

L
series

Engine
Mechanical

Tool
number
For

Referenl
t

No
Description
use

page
or

tool
name
Unit

mm
in

on

Figure
No

S
KV10
1039S0

Valve

guide
reamer
This

guide
is
used
for
All

Fig
EM
44

set

o

Pressing
used

guide
out
of

place
L
series

0

Driving
a
new

guide
into

place
and

STIlO81000

0

Finishing
the
bore
of
new

guide
A
series

Reamer

12
2
mm
dia

STlI
032000

Reamer

8
0

mm
dia

STl1320000

Drift

V

SE192

6
STll6S0001

Valve
seat
cutter
set
This
valve

seat
cutter
set
is

used
to
or
refinish

a
valve
seat
All
Fig
EM
4S

L

series

7
STl2070000

Valve
lifter
SE193

This
t
ol
is
used

to

compress
valve

spring
by
the
combined

action
of
its
eam
and

lever

thereby
facilitating
the

removal

or
installation
of

valve
collet
for

general
use
All

models
Fig
EM
32

Fig
EM
8l

SE194

EM
34