Carbon Fouled; Oil Fouled; Overheating; Cleaning And Regap - Datsun 1200 1971 Workshop Repair Manual

Icnition Sptem
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Carbon fould
Fig 85 Spark plug
Life
plug
heat range
Carbon
fouled
Dry fluffy
carbon
depo
lts
on
the
Insulator and electrode
were
mostly
caused
by
slow
speed dnvlng
In cIty
weak
Ig
nltlOn too
nch fuel
mixture dirty
aIr
cleaner
etc
It
IS
advIsable
to replace
WIth
plugs havmg
hotter
heat
range
011
fouled
Wet black
depoSits
show
excesSive
oIl entrance Into combusllon
chamber
through
worn
rmgs and pIstons
or excessIve
clearance
between
valve
gUIdes
and stems If the
same
condition
remams
after repair
use a
hotter
plug
Overheatmg
WhIte
or
hght
gray
msulator
WIth black
or
gray brown
spots
and blUIsh
burnt electrodes indIcate engme
overheatIng
Moreover th
e appearance
results from
in
correct
IgnitIon tIming loose
spark plugs
low
guel
pump pressure
wrong selectIOn of fuel
a
hotter plug
etc
It
IS
adVisable
to replace WIth plugs havmg
colder heat
range
After
cleaning
dress electrodes With
a
small
fine file
to flatten
the surfaces
of both
center
and Side electrodes
In
parallel
Set
spark plug
gap
to
specification
FIg 86 Settmg spark plug
gap
Install
spark plugs
and
torque
each
plug to
11
to
15 ft Ib
Connect
spark plug
wires
Cleaning
and
Regap
Clean
spark plugs
In a
sand
blast type
cleaner AVOId
excessIve
blasting Clean
and
remove
carbon
or
OXide
depoSits
but do
not
wear
away
porcelain
If
depos1ts
are
too
stub
born discard plugs
After cleaning spark plugs
renew
firing
sur
face of electrodes With file mentioned above
Then gap
spark plugs
to 0 030
to
0 035
In
uSing
a
round
wire
feeler
gauge
All
spark
plugs
new or
used should have
the
gap
checked and
reset by bending
ground
electrode
II