Ignition System; Ignition Timing; Ignition Distributor: Maintenance/Adjusting The Contact Breaker Gap - Datsun 510 series Workshop Manual

IgnItIon System
DESCRII TION
IGNITION TIMING
IGNITION DISTRIBUTOR Maintenance
ADJUSTING THE CONTACT BREAKER GAP
CENTRIFUGAL ADVANCE MECHANISM
VACUUM ADVANCE MECHANISM
IGNITION DISTRIBUTOR Removal and
Dismantling
IGNITION DISTRIBUTOR
Assembling
and Installation
SPARKING PLUGS
DESCRII TION
The ignition circuit comprises the distributor ignition coil
ignition switch spark plugs high tension lead and the battery
See
Fig C 1
The Hitachi distributor is shown
in
exploded form in Fig
C 2 19niton timing is automatically regulated by the distributor
centrifugal advance mechanism
or vacuum
advance mechanism
depending upon
the demand made
on
the
engine
The
vacuum
advance mechanism operates under part
throttle only and
uses
intake manifold depression
to
advance the
ignition timing
When the
engine speed
is increased the
vacuum
is inoperative and
ignition timing
is
regulated by
the
centrifugal
advance mechanism
The centrifugal advance mechanism uses a
system of
governor
weights and springs which
turn
the
carn
assembly in
on
anti cl o ckwi s e
direction to advance the
ignition timing
As
the
engine speed
is decreased the
weights
move
back and allow the
cam
to return thereby retarding
the
ignition timing
The ignition coil is
an
oil filled unit comprising
a
coil
around which is wound the
secondary
and
primary windings
The
number of
turns
in the
primary winding provide
a
high secondary
voltage throughout the speed range The resistor is
automatically
by passed
at
the
moment
of starting and allows the ignition
coil
to
be directly connected
to
the battery This
applies the
full battery voltage
to the
coil
to
give the
necessary
staTting
boost
When the
starter
switch is released the
current
flows
through
the resistor and the
voltage through
the coil is
dropped
for
normal
running
purposes
IGNITION TIMING
The ignition timing
can
be accurately checked using
a
stroboscopic timing light which should be connected in
accor
dance with the manufacturers instructions
Make
sure
that the
timing
marks
on
the crankshaft
pulley
are
visible if they
are
not
visible mark them with chalk
or
white
paint
Each mark
represents a
50 division of the crank
angle
Disconnect the distributor
vacuum
line start the
engine
and allow it
to
run
at
normal
idling speed
or
slightly
below
Point the timing light
at
the timing pointer
on
the front
cover
Fig
C 3 The crankshaft
pulley
groove
should appear
to be
stationery
and
aligned
with the
pointer
on
the front
cover
The
top
dead
centre
mark is located at the extreme right
as
shown in the illustration
If the setting requires adjustment the
distributor flange bolts
must
be slackened and the distributor
body
turned clockwise
to
advance
or anti cl o ckwi s e
to
retard
the timing
See Technical Data for
timing settings
After
adjusting
the timing tighten the distributor flange
bolts and recheck the
timing
IGNITION DISTRIBUTOR Maintenance
Remove the distributor cap by easing
away
the
two
clamps
and examine
the
points
for
signs
of
burning
or
pitting
The
points
can
be cleaned
if necessary
using
a
fine
grade
of oilstone
or
file The faces of
the
points
must
be completely flat and
parallel
and all abrasive dust removed with compressed air If
the points
are
excessively pitted they
must
be renewed and grease
applied
to
the moving
contact
pivot
and the surface of the
cam
Ensure that the distributor cap is
thoroughly
clean both inside
and outside A contaminated cap will
promote tracking
indicated
by
black lines and caused
by
electrical
leakage
between
the
segments on
the inside of the
cap
Make
sure
that the
carbon button is not
worn
Both the distributor cap and
rotor
must
be renewed if
they
are
cracked
or damaged
IGNITION DISTRIBUTOR
Adjusting
the
contact
breaker gap
To
adjust
the
contact
breaker
points
remove
the distributor
cap and pull the
rotor
off the
cam
spindle
Turn the
engine
until the heel of the
contact
breaker
arm
is
positioned
on
the
cam
lobe the contact
breaker gap is
set to
the maximum
in
this
position
Slacken the
adjusting screw Fig
CA
insert
a
feeler
gauge
between the points
and
adjust
the breaker
plate
until the
re
quired
gap
of 0 4 5 0 55
mm
0 0177 0 0217
in
is obtained
Tighten the adjusting
screw
and recheck the setting
After
the
contact
breaker gap has been
adjusted
check the ignition
timing
as
previously
described
The tension of the
contact
breaker should be 0 5 0 65 kg
I
I I 4 lb Measure the tension with
a
gauge and
at
900
to
the contact
breaker
arm
29