Fitting Electronic Ignition

Over the last 10 years or so, a number of companies have developed kits which allow traditional ignition systems to be converted to modern electronic ignition (EI). These kits replace the points in the distributor, eliminating the most fault-prone aspect of the traditional setup, and require little to no maintenance or adjustment.They usually fit under the distributor cap, and are discreet and completely reversible.

The following Tutorial shows how to convert a Lucas distributor to electronic ignition using one of the smaller system which fit inside the distributor cap. These are available readily from around £30, and can be fitted to a number of other distributor makes. If in doubt, consult your car's service manual.



Before carrying out any work on the ignition system, it is essential that the battery should be disconnected.

Tools
  • Assortment of screwdrivers
  • Small socket/adjustable wrench 
  • Wire crimpers
  • Long-nose pliers 
  • Multimeter 
  • Lengths of automotive wire 
  • Spade connectors or other electrical connectors
  • Degreasing agent 
  • Lint-free rag 
  • Capful of engine oil
  • White heat grease
1 - Remove Points/Condenser
Remove the distributor cap and lift off the rotor arm. When removing the distributor components, it is a good idea to take them out as one complete assembly. Begin by removing the points securing/adjustment screw and set it aside. Next remove the small screw holding the capacitor to the distributor base plate. By sliding the low-tension block connector upwards, it should be possible to remove the whole assembly.

2 - Strip Distributor
If it has been an unknown duration since the distributor was last serviced, it is a good idea to strip it further to inspect for damage or wear. If this is not considered necessary, proceed to step 3.
Remove the two small screws securing the distributor base-plate to the body - these are located in the small recesses at the edges of the plate. With a pair of long-nose pliers, carefully lift the vacuum advance spring off the pin. Remove the whole distributor base plate as one unit.
Rotate the two halves of the base plate against each other until they separate. Inspect the braided electrical wire for wear, check that the sprung steel bracket is intact, and clean the whole assembly thoroughly with a degreasing agent.

Next inspect the inside of the distributor body. Check that there is no play in the distributor drive shaft - any sideways movement indicates excessive wear, and the whole unit should be removed for a complete overhaul. Check that the centrifugal weights operate correctly (they should splay outwards with a clean, crisp movement when the distributor drive shaft is turned in reverse), and that the springs are in good condition and secure. Ensure that there is no foreign matter in the base of the distributor - over a period of years, small grub screws and nuts may have been dropped down during a routine point/condenser change. Remove any loose matter, as this can cause terminal wear if left. 
If any of the parts in the distributor base are worn or damaged excessively, the distributor must be removed from the car and overhauled separately.
As far as possible, the inside of the distributor body should be cleaned with a lint-free rag. DO NOT pour any degreasant or other cleaning agents into the body as they could easily seep into the engine oil and contaminate it.
Rub a little engine oil onto the centrifugal weights and springs, and pour no more than a teaspoonful into the base of the distributor to lubricate the drive shaft. 

Reassemble the distributor base plate, clean the area around the securing screws and reinstall it. Ensure that the screws are tight, clean and have their washers, and that the base plate wire is attached with a good, clean connection (use emery paper if necessary to achieve a clean contact). Carefully reattach the vacuum advance spring.


3 - Test for Continuity
With the distributor base plate attached to the distributor body, use a multimeter and check for electrical continuity. 
First check that there is no electrical resistance between the distributor base plate and the body. If there is any other reading besides nil, it is almost certainly the distributor base plate wire that is at fault. This should be replaced as a matter of course if there is any visible wear to its insulation or contacts.

Next check that there is no resistance between the distributor and the nearest earth point on the vehicle. Normally, there is one or more a large earth straps linking the engine to the chassis or engine bay. Wipe away any surface dirt and check for continuity between this and the distributor base plate.

If the multimeter is showing any resistance at this point, the distributor is incorrectly earthed and must be removed for inspection, cleaning and reinstalling.
Finally, check the wire between the distributor low-tension block and the negative side of the ignition coil for continuity. 

4 - Install Electronic Ignition Kit
After ensuring that the distributor base plate is clean and free from grease or oil, take the EI unit and liberally apply the white heat grease to the underside of its mounting plate.

Place the hole in the EI unit over the old points pin on the distributor base plate and then screw the other side down loosely using the old points securing screw.
Take the trigger ring and place it over the distributor cam, ensuring that it fits snuggly down onto the spindle. 
Using the EI unit securing screw, adjust the position of the unit relative to the trigger ring so that the distance between the ring and the unit is relatively equal along the length of the unit. 
Also, check that this gap does not vary too much as the distributor drive shaft is rotated. If there is significant variation of this gap as the drive shaft is rotated, the distributor will need to be removed and rebuilt. Screw the EI unit down tightly.
Route the EI unit's wires around the edge of the distributor base plate and slide them through block to ensure they are neatly arranged and there is no excess wire in the distributor, and that the wire is not strained.
Next slide this block into the cutout where the low-tension block had previously been. Using spade connectors, block connectors or solder, connect the black (or blue) negative wire from the EI unit to the wire running to the negative side of the ignition coil.
Extend the red (positive) wire so that it reaches the ignition coil. Using a spade connector or other electrical joint, connect this red wire directly to the positive side of the ignition coil.

5 - Test the System
With the new ignition system fitted, it is a wise idea to carry out a final set of checks before attempting to start the engine.
First ensure that all of the wiring is correctly located, that the coil is connected to both the positive and negative side of the EI unit, the main positive from the ignition switch and the ballast resistor or tachometer is one is fitted.

Inspect the rotor arm for signs of black deposits (this is indicative of a fault on the high-tension side of the ignition, and must be remedied separately to the points/condenser overhaul - see the overhaul guide to rebuilding the HT circuit for more information). With a clean lint-free rag, carefully wipe the brass top surface of the rotor arm to remove any build up of grime. If it is necessary to clean the edge of the rotor arm, gently rub the edge against a clean tyre wall in straight lines. Under no circumstances should any abrasive force be applied to the rotor arm - this would result in difficulty transferring an electrical pulse cleanly and cause sparking inside the distributor cap rather than the spark plugs.

Carefully wipe out the inside of the distributor cap and gently pull the carbon brush out by a fraction to ensure a good contact with the rotor arm. Seat the rotor arm securely on top of the drive shaft and replace the distributor cap, ensuring the HT leads are all correctly connected.
Reattach the battery and start the engine. With the engine warmed to normal operating temperature, the carburettor should be adjusted to the new ignition. 
The more efficient nature of electronic ignition will partly increase engine economy: carburetion should therefore be checked as a matter of course after conversion. A colour tuning kit as described in the Maintenance | Fueling section of the Step-by-Step guides is the most effective method.

Over a carefully planned route, test the engine's responsiveness under hard acceleration. Evidence of pinking or sluggish performance may be indicative of incorrectly set timing, which is a common occurrence due to the trigger ring not triggering the EI unit at precisely the same point that the original points/condenser system had done so. Simply reset the timing and assess again. 

6 - Maintenance
The biggest benefit of EI over the traditional ignition setup is their maintenance free operation. No adjustment is possible, and none should be necessary in their lifetime. Nevertheless, for the first couple of hundred miles, it is a worthwhile exercise to regularly recheck the timing and carburetion, making any necessary adjustments in that order. The security of the EI unit to the distributor base plate should also be checked, as should the distance between the trigger ring and unit. Every 1000 miles or so (or after prolonged motorway driving), it is worth removing the EI unit to reapply the white grease to its underside. Heat is the killer of all electronic products, and maximizing the effectiveness of the heat sink is a wise move in prolonging the life of the system.
A well maintained electronic ignition system should give improve starting, increase performance and economy, and generally trouble-free motoring. Inherent unreliability issues are yet to be reported with the majority of manufacturers, and for the most part these systems seem to be the cure to a multitude of problems for many classic owners.

For more information on routine maintenance of your ignition system including the HT circuit, see the Troubleshooting section in the Step-by-Step Guides section.

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