ELECTRICAL EQUIPMENT
giving maximum opening, slacken the
4.
SERVICING
screw(s) securing the fixed contact
plate and adjust its position to give the
Before starting to test, make sure that the
required gap. Tighten the
screw(s).
battery is not fully discharged, as this will
Recheck the setting for other positions
often produce the same symptoms as a
of the engine giving maximum opening.
fault in the ignition circuit.
3.
DESIGN
DATA
(a) Firing angles
:
On,
90°, 18O0, 270°,
&l0.
Closed period
:
60"
&
3".
Open period
:
30"
f
3".
(b)
Contact breaker gap
:
0.014" to 0.016"
(c)
Contact breaker spring tension, meas-
ured at contacts
:
20-24 ozs.
(d)
Capacitor
:
0.2 rnicrofarad.
(e) Rotation
:
Anti-clockwise.
(f
)
Checking Automatic timing control
:
(i)
Advance due to centrifugal con-
trol
:
Set to spark at zero degrees at
minimum r.p.m.
Run distributor at 2,700 r.p.m.
Advance should lie between 13"
and
15".
Check advance at following de-
celerating speeds
:-
Speed
r.p.m.
2,OOo
750
600
200
Advance
(degrees)
129-144
S~-lO+
64- 9
0-2
Part
No(s). of auto advance
springs
:
421218, 421219.
(C)
Advance due to vacuum control
:
Apply a vacuum of 18" of mercury.
Advance to lie between
6"
and 8".
Check advance at the following
points, as the vacuum is reduced
:
Vacuum
(in hg.)
94
4f
Advance
(degrees)
5-7
No advance below 2" of mercury.
(a) Testing
in
Position to Locate Cause
of Uneven
Firing
Run the engine at a fairly fast idling
speed.
If possible, short circuit each plug in
turn with the blade of an insulated
screwdriver or a hammer head placed
across the terminal to contact the
cylinder head. Short
circuiting the
plug in the defective cylinder will
cause no noticeable change in the
running note. On the others, however,
there will be a pronounced increase in
roughness. If this is not possible, due
to the
sparking plug being fitted with a
shrouded cable connector, remove each
plug connector in turn. Again, re-
moval of the connection to the defec-
tive cylinder will cause no noticeable
change in the running note, but there
will
be a definite increase in roughness
when the other plugs are disconnected.
Having thus located the defective
cylinder, stop the engine and remove
the cable from the sparking plug
terminal.
Restart the engine and hold the cable
end about
A"
from the cylinder head.
If sparking is strong and regular, the
fault lies with the sparking plug, and it
should be removed, cleaned and ad-
justed, or a replacement fitted. If,
however, there is no spark, or only
weak irregular sparking, examine the
cable from the plug to the distributor
cover for deterioration of the insula-
tion, renewing the cable
if
the rubber
is cracked or perished. Clean and
examine the distributor moulded cover
for free movement of the carbon brush.
If a replacement brush is necessary, it
is important that the correct type is
used. If tracking has occurred,
in-
dicated by a
thin
black line between
two or more electrodes or between one
of the electrodes and the body, a
replacement distributor cover must be
fitted.
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