9 Using a short screwdriver, unscrew the
single screw securing the adjustable contact
breaker plate to the distributor baseplate. Lift
off the screw and washer, taking care not to
drop them inside the distributor.
10 Lift the contact assembly off the
baseplate and detach the tensioning arm from
the insulator. Release the terminal containing
the condenser and low tension leads from the
end of the arm and then lift away the contact
breaker points (see illustrations).
11 To refit the points first engage the terminal
containing the condenser and low tension
leads with the end of the tensioning arm.
Make sure that the black lead is uppermost.
12 Position the tensioning arm in the
insulator, place the contact assembly on the
baseplate and refit the retaining screw and
washer.
13 The contact breaker points gap should
now be adjusted as described in the previous
Section.
Ducellier
14 Remove the distributor cap as described
in the previous Section then withdraw the
rotor arm from the distributor spindle.
15 Disconnect the contact breaker low
tension lead at the connector.
16 Using a small screwdriver or pointed-nose
pliers, carefully extract the circlip securing the
moving contact arm to the pivot post.
Remove the washer and lift off the moving
contact arm and low tension lead assembly.
17 Unscrew the single screw securing the
adjustable contact breaker plate to the
baseplate. Lift off the screw and washer
taking care not to drop them inside the
distributor. Now lift away the breaker plate.
18 To refit the points first position the
adjustable contact breaker plate on the
baseplate and refit the retaining screw and
washer.
19 Place the moving contact arm over the
pivot post and engage the tensioning arm with
the insulator. Refit the washer and circlip to
the pivot post.
20 Enter the grommet of the low tension lead
into the slot on the side of the distributor and
reconnect the lead.
21 The contact breaker points gap should
now be adjusted as described in the previous
Section.
7 Condenser - testing, removal
and refitting
2
Note: Carburettor models without electronic
ignition may be fitted with either a Lucas
23D4, 25D4, 45D4, 59D4 or Ducellier
distributor. Identify the unit being worked on
by referring to the illustrations accompanying
Section 5, then proceed as described below
according to distributor type.
Testing
1 The purpose of the condenser (sometimes
known as a capacitor) is to prevent excessive
arcing of the contact breaker points, and to
ensure that a rapid collapse of the magnetic
field, created in the coil, and necessary if a
healthy spark is to be produced at the plugs,
is allowed to occur.
2 The condenser is fitted in parallel with the
contact breaker points. If it becomes faulty it
will cause ignition failure, as the points will be
prevented from cleanly interrupting the low
tension circuit.
3 If the engine becomes very difficult to start,
or begins to miss after several miles of
running, and the contact breaker points show
signs of excessive burning, then the condition
of the condenser must be suspect. When
examining the contact breaker points,
disregard any blue discoloration which may
be apparent on their faces. This is due to the
formation of tungsten oxide, and has no
detrimental effect on ignition performance; it
is not indicative of condenser failure. A further
test can be made by separating the points by
hand, with the ignition switched on. If this is
accompanied by an excessively strong flash,
it indicates that the condenser has failed.
4 Without special test equipment, the only
reliable way to diagnose condenser trouble is
to renew the suspect unit and note if there is
any improvement in performance.
5 Removal and refitting of the condenser
varies according to distributor type as follows.
Removal
Lucas 23D4 and 25D4
6 Remove the distributor cap and rotor arm,
referring to Section 5 if necessary.
7 Undo and remove the nut and washer (if
fitted) from the contact breaker terminal post.
Withdraw the flanged nylon insulator and
release the condenser lead.
8 Undo and remove the small screw securing
the condenser to the distributor baseplate and
lift the condenser away.
Lucas 45D4 and 59D4
9 Remove the distributor cap and rotor arm,
referring to Section 5 if necessary.
10 Release the contact breaker points
tensioning arm from the insulator and detach
the condenser and low tension lead terminal
from the end of the arm.
11 Undo and remove the small screw
securing the condenser to the distributor
baseplate.
Ignition system 5B•9
5B
6.8 Lift off the rotor arm . . .
6.10a . . . and with the retaining screw removed, lift the contact
assembly off the baseplate
6.10b The LT terminal can then be detached from the
tensioning arm
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