Electronic Ignition Kit - to fit or not to fit?

If an engine stops or runs poorly it is often due to a problem within the distributor relating to the points, condenser or general wear. Regular maintenance can minimise these problems but wear will always be present.

It is not uncommon on 2½ litre cars for oil to find its way into the distributor as the drive to the distributor is taken from the middle of the front inlet cam shaft bearing and oil which creeps up into the distributor is sure to lead to problems. A small hole drilled through the bottom of the distributor helps the oil escape but some will still find its way onto the points.

Wear in the distributor bushes and spindle causes a variation in the points gap which affects both the dwell angle and the ignition timing as well as making it difficult to set the points gap correctly. Play between the spindle and the cam will give similar problems. The points gap will also close up as the plastic heel on the points wears. This can be due to roughness on the cam or poor quality plastic.

To make matters worse, several people have commented that some modern replacement points are of poor quality often with the points not closing to give full face contact. There are similar reports about condensers which fail very quickly. Clearly there are several places within the distributor where problems can arise so is an electronic ignition kit the solution?

There is a large range of electronic ignition kits now available and a good place to see the range is Ebay. It is even possible to find kits which include a new base plate with the trigger head already attached to it both for the early Bakelite base plates distributors and the later metal base plate ones. This makes fitting very easy. The question is: do they really overcome the problems and are they worth the money? They all claim to give better fuel economy, better starting and smoother running and in general these claims are met. They use a triggering head fitted to the base plate which takes the place of the points and this is activated by a sleeve fitted over the cam each time a cam lobe passes the trigger head. Since there is no direct electrical connection between the sleeve and the trigger head there is nothing to arc and burn so no maintenance is needed. With no points pushing on the cam there is less wear on the distributor bushes. The gap between the sleeve and the trigger head is not critical so slight wear and hence wobble in the distributor has negligible effect as does oil in the distributor. Of course there is no condenser to fail either. Modern petrol cars use electronic ignition and these do not have a history of problems so these kits should be more reliable than the old points system.

So much for theory but how do they work in practice? The first system I used was made by Mobelec and I fitted it many years ago to my RMF. It comprised an electronics box and a trigger head. The electronics in the box enabled the spark pulse to be shaped for enhanced performance. I made a new base plate for the distributor and fitted the trigger head to it. I fitted the electronic box to the inner wing under the carbs. where it could not been seen. This particular kit was for +ve earth and I fitted similar kits for -ve earth to my RMB and to a friend's RMB. The kit on my RMF is still working well. I have lost touch with the RMBs but when last seen they were working well too. All three cars suffered from oil in the distributor but all ran faultlessly with slightly better fuel consumption - a total success.

The kits currently available on Ebay are simpler than the Mobelec ones above having no electronics box. This makes fitting very simple but looses the pulse shaping ability. So far I have only fitted one of these which was -ve earth and included a new base plate. Fitting involved removing the old base plate, fitting the new one, connecting up a couple of wires, sliding the sleeve over the cam and giving the ignition timing a fine tune. It was very easy and quickly done as well as being virtually undetectable. I have left the old base plate in the car just in case anything goes wrong but I do expect to use it. After all, I have carried the old base plates in my RMF and RMB for many miles and never had to use them. I cannot comment yet on fuel consumption but the engine is running very smoothly. The illustration shown here is typical of a kit including a new base plate. The blue plastic sleeve fits over the cam.

As regards costs, a kit on Ebay costs in the region of £40 to £50 depending on the make and whether a base plate is included. The one illustrated here is for for +ve earth and retails at £49.99 including P&P at the time of writing. Compare this to a new set of points at about £16 and a new condenser at about £5 and how often these will have to renewed. Also consider the cost of refurbishing a distributor which has worn bushes or worse. There may also be a saving on petrol too. Clearly there is potential for a considerable cost saving over the forth coming years as well as an improvement in running and reliability.

The only obvious drawback is a departure from originality which is unlikely to be noticed as the only indication is an extra small wire running to the distributor..

So if you want your ignition system to be as reliable and trouble free as those on modern cars, why not make the change? You might extend the life of your distributor too.