moves freely in its
holder
and
examine
the
moulding closely for signs
of
breakdown.
After
long service, It may have
become
tracked,
that
is, a
conducting
path may have
formed
between
two
or
more
of
the
electrodes
or
between
one
of
the
electrodes
and
some
part
of
the
distributor
in
contact
with
the
cap.
Evidence
of
a
tracked
cap is
shown
by
the
presence
of
a
thin
black line in
the
places
affected. A
replacement
distributor
cap
must
be fitted In place
of
one
that
has
become
tracked.
Low-tension
circuit:
Testing
In
position
(a) Spring back
the
secu ring clips on
the
distri-
butor
and
remove
the
moulded cap and
rotor.
If
the
rotor
Is a
tight
fit. It can be
levered
off carefully
with
a
screwdriver.
(b)
Check
that
the
contacts
are
clean and
free
from
pits,
burns,
oil
or
grease.
Turn
the
engine and
check
that
the
contacts
are
opening
and closing
correctly
and
that
the
clearance
when
the
contacts
are
fully
opened
Is
between
·010 In. and ·012 in. (,25 mrn,
and
·30 rnrn.) on
dl
strl
butors
No.
40162D and ·014 In. and
-016 in.
('36
rnrn.
and
·il
mm.) on
distributors
40162 E0 nwards.
Correct
the
gap If necessary.
(See
Section
C.li.)
(c)
Disconnect
the
cable
at
the
contact
breaker
terminal
(CB)
of
the
coil and
at
the
low-
tension
terminal
of
the
distributor,
and
connect
a
test
lamp
between
these
terminals.
If
the
lamp lights
when
the
contacts
close and
goes
out
when
the
contacts
open,
the
low-
tension
circuit
Is In
order.
Seetion
£.2
TESTING
LOW·TENSION CIRCUIT
CONDENSER
SCREIAIS
SECURINC
CONTACT
PLATE
Fig.
C.I.
The
distributor
with
the
cover and
rotor
arm removed,
showing
the
contact
breaker
mechanism.
C
TIlti
IGNITION
EqUIPMENT---~-.
Section
(;.1
LOCATING
THE
CAUSE
OF UNEVEN
FIRING
To
test wfth
sparking
plugs
In
position
(a)
Start
the
engine
and
set
It
to
run
at a falrly
fast Idling
speed.
(b) S
hert-el
rcu It each plug In
turn
by placlng
a
hammer
head
or
the
blade of a
screwdriver
with
a
wooden
or
insulated handle
between
the
terminal
and
the
cyllnder
head.
No
difference
In
the
engine
performance
will be
noted
when
short-circuiting
the
plug In
the
defective
cylinder.
Shorting
the
other
plugs will make
uneven
running
more
pronounced.
(c) Having located
the
cylinder
which Is
at
fault,
stop
the
engine
and
remove
the
cable
from
the
terminal
of
the
sparking plug.
Restart
the
engine and hold
the
end
of
the
cable
about
-fir
In. (4,8 mm.]
from
the
cylinder
head.
(d) If
the
sparking Is
strong
and
regular,
the
fault
probably lies in
the
sparking plug. Remove
the
plug, clean. and
adjust
the
gap
to
the
cor-
rect
setting
or
alternatively
fit a
replacement
plug. (See Section C.4.)
(e) If
there
Is no
spark
or
lf
lt
Is
weak
and
Irregular,
examine
the
cable
from
the
sparking
plug
to
the
distributor.
After
a long period
of
service
the
rubber
Insulation may be
cracked
or
perished,
In which case
the
cable should be
renewed.
Finally,
examine
the
distributor
moulded
cap.
wipe
the
inside and
outside
with
a clean
dry
cloth.
see
that
the
carbon
brush
Low-tension
circuit-to
locate
fault
(0) Having
determined.
by
testing
as preViously
described,
that
the
fault lies in
the
low-tension
circuit,
switch
on
the
ignition, and
turn
the
engine until
the
contact
breaker
points
are
fully
opened.
(b) Refer
to
the
wiring
diagram and
check
the
circuit
with
a
voltmeter
(0-20
volts)
as
follows
:-
Note.-If
the circuit Is In order the
reading
on the voltmeter should be approXimately
12 volts.
(c) Battery to
starter
switch
terminal.
Connect
a
voltmeter
between
the
starter
switch
terminal
C.2
M.G. Midget. Issue 5 (H & E)
95781-9/55
Wishvilles Classic
Automobile Library
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