How to… fit electronic ignition to your classic car

By Classic & Sports Car Editorial team

| 29 Aug 2019

Classic & Sports Car – How to… fit electronic ignition to your classic car

Most 1950s-’70s cars have contact-breakers or ‘points’ to optimise the delivery of the spark on each cylinder’s combustion stroke.

But points need regular adjustment to ensure that they close for the precise duration needed for the coil to charge between the breaks in the low-tension circuit that force the coil to deliver a spark.

Plus, the lower volumes now needed and use of inferior materials has led to poorer component quality and premature condenser failure, which can leave you stranded.

Electronic ignition has fewer moving parts, typically using an optical or magnetic (Hall effect) sensor to detect when the LT current needs to be ‘broken’.

Installation varies: some types bolt under the distributor cap (such as Lumenition Magnetronic and Aldon Ignitor), while others have a separate amplifier.

If your dizzy is worn out, an all-in-one replacement (such as 123ignition) also offers switchable advance curves, but the standard position on any unit should exceed OE settings.

Check the kit is the correct polarity for your car. Ensure the engine is correctly timed (for set-ups not replacing the distributor) and feel for any play in the dizzy shaft before starting. Test drive over the same route before and after to check performance.

1: UNCLIP DISTRIBUTOR CAP

Disconnect the battery then take off the distributor cap and secure it out of the way.

Pull off the rotor arm and then remove the low-tension wire that runs from the distributor to the coil. This wire, along with the plastic insulator plug that sits in the outer wall of the distributor, is no longer needed.

2: REMOVE CONDENSER/POINTS

Electronic ignition does away with the need for a traditional condenser and points, so these need to be removed by unscrewing them from the distributor base-plate.

Kits such as these can often be easily swapped over in case of failure, so keep the old parts in your toolkit just in case you need to perform a roadside repair.

3: SCREW IN MOUNTING PLATE

With the points extracted, clean up the distributor and get rid of any excess grease or dirt. This is also a good opportunity to lubricate its shaft with a drop of oil.

Fit the module mounting plate to the dizzy with the screw provided, making sure that it locates on the brass pin on which the points used to pivot.

4: INSTALL IGNITION MODULE

Fit the electronic unit on to the mounting plate with the screw provided. Feed the wires from the module around the inside of the distributor and through the new plastic side plug.

Gently rotate the distributor base-plate to ensure that the wires aren’t pulled tight when the vacuum advance is operating.

5: PRESS TRIGGER DISC ON

Fit the trigger disc to the top of the distributor shaft. Make a note of which way the rotor arm faces when it is in place and then match this to the indicator mark (a small round dot) on the disc.

Once aligned, push the disc firmly into place, making sure that the wires are not trapped, then refit the rotor arm and cap.

6: EXTEND WIRING IF NEEDED

Depending on the location of your coil, you may need to extend the module’s wires. Crimped or soldered terminals are acceptable, but make sure that they are secure.

Also ensure that the wire you use is 5A or more and can handle the current load. Route these safely and away from any potential chafing.

7: REPLACE THE OLD COIL

Although it’s not imperative, we replaced the coil on this negative-earth set-up with the higher-output Mega Spark 3 recommended by Lumenition, which requires a ballast resistor to be fitted.

Remove the ignition wire from the coil’s positive terminal, take off the HT king lead and then unscrew the unit.

8: FIT BALLAST RESISTOR/COIL

Connect the positive terminal of the coil to one side of the resistor. Attach the ignition feed to the other side of the resistor then the black wire from the ignition module to the coil’s negative terminal.

Connect the red wire to the resistor on the ignition feed side and refit the HT king lead. Connect battery and check timing.

USEFUL CONTACTS