Lumenition Optronic PMC-50 (positive earth)

[svenedin]

I decided to fit an electronic ignition system to Xavier today. I am a bit of an originality freak in some respects but I took the plunge.

I helped my father fit a Lumenition system to his Mercedes 230 (it was a 1968 model) in the 1970's. I was only a child then but I remember how pleased my father was with the new system. We had seen Lumenition on "Tomorrow's World" with Raymond Baxter.

I researched electronic ignition systems quite extensively. Lumenition Optronic is amongst the most (if not the most) expensive on the market. It is British designed and British made and the company are based near the Elephant and Castle in London. It is generally regarded as bombproof and its reliability is legendary.

Anyway, I had thought the Optronic system was not suitable for my car because on the ESM website it says "for negative earth only". I happened to discover that this is incorrect and that by being wired in a different way it can be used on positive earth cars too. I also discovered that there is a mounting bracket for the main module that means that it does not have to be mounted on the bulkhead or wing and no holes have to be drilled in the car. It therefore fits my "no permanent modification" stipulation.

Installation was fairly straightforward. The only real problem was that I found that the chopper blade will foul in a Lucas 25D with the long points mounting post. Of course it had to be that the distributor in my car IS a long post 25D.......Fortunately, I had spare rebuilt Lucas 25D with the short post so I swapped them around and all went well.

Once everything was installed I took a deep breath and turned the ignition key. The engine started first time despite the weather being very cold (close to freezing). I did some small adjustments to the ignition timing using the strobe and also checked the fuel mixture.

So that's it. I need to do a test drive and if that goes well I need to tidy up the wiring. All the wiring is miles too long and untidy but I do not want to cut it shorter until I know everything is as it should be.

Stephen

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[Classiccars]

I find the electronic ignition give me peace of mind to those that are not the best mechanics or don't want the stress of points.Also prefer original but this is a great help I find.

[svenedin]

I find the electronic ignition give me peace of mind to those that are not the best mechanics or don't want the stress of points.Also prefer original but this is a great help I find.

I ran on points for 34 years and they didn't give me that much trouble really. They do need maintenance of course and parts quality is not what it was, especially condensers. I have a rebuilt distributor set up with points as a "drop in" unit should I feel the need to go back. That is a "long post" Lucas 25D that takes the better two-piece fibre heeled points that Distributor Doctor sells. The later 25D has a short post that takes a slightly different one-piece plastic heeled type points set. I did find over the years that the car was not very happy starting in the cold and damp although it always did start eventually even if I flattened the battery and ended up using the starting handle! I am getting a bit older now and less inclined to mess about and I am not the only family member to drive the car. I may be able to fix many things by the side of the road but other people cannot and the car is not just a toy, it is sometimes the only car available so it has to work without fuss every time.

Anyway, the PMC-50 kit came with a Lumenition Megaspark 4 1.5 Ohm coil. This coil has to have an external ballast resistor of 1.5 Ohms to bring the total resistance to 3 Ohms as with a standard coil. I did not particularly want a kit with a new coil but the price of the PMC-50 kit was only a few pounds more expensive than just buying the electronic bits and the mounting bracket. Effectively the new coil and ballast resistor was almost free. I fitted the new coil and ballast resistor today. It all fits neatly (pictures to follow once wiring tidied up). On firing up the car with the new coil it does seem to run extremely well. The only issue I found was that I got electromagnetic interference that caused the tell tale bulb at the end of the indicator stalk to flicker at a speed proportional to the engine speed. I assumed that is because the new coil is more powerful and I am using copper cored high tensions leads with no suppression. I fitted 5 K Ohm suppressed spark plug caps and the tell tale bulb now flickers very dimly. If I used 10 K Ohm caps I think it would not flicker at all. It should be said that I have an electronic flasher relay and not the standard bimetallic strip can relay. I have never had a setup with a ballast resistor before. I noticed that the ballast resistor gets hot but the coil stays cold. This suggests the coil should have an extended service life.

I enquired with Autocar Electrical (the makers of Lumenition) whether I would invalidate the warranty if I cut the cables and fitted new connectors to make a neat and tidy installation. They were very helpful and told me to go ahead and tidy things up and that if I ever found that I wanted to move the unit they could supply a new loom for the main unit. Good to know.


Stephen

[svenedin]

I tidied up the wiring today. I cut the cables shorter (they were far too long). Crimped on new terminals and fitted a new mate and lock connector. Covered the cables in heat shrink tubing with loom tape over the top. The cables now look very similar to the original loom. I have left them longer than they strictly need to be in case I need the extra at a later date. The spark plug caps (5 K Ohm) are a bit jazzy in red but that was all that I could get. I think I'll replace the modern insulated crimped spade terminals with the older type with clear plastic insulation or with ring terminals with clear insulation. Those red and blue modern crimps don't like right to me. Little details bother me.

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[Sleeper]

Re. the crimps, invest in a felt tipped pen , that's what I do...

John ;-)

[svenedin]

Re. the crimps, invest in a felt tipped pen , that's what I do...

John ;-)

Yes they'd look better if they were black. The other option would be to use uninsulated brass ring terminals for the coil connections. Arguably they are more secure anyway. For now the black Sharpie will be used. Thanks for the tip!

Stephen

[kevin s]

I've found lumenition to be great, only question I would have is is it rated to be fitted to the engine? Electronics don't generally like a lot of vibration, mines on the inner wing.

[svenedin]

I've found lumenition to be great, only question I would have is is it rated to be fitted to the engine? Electronics don't generally like a lot of vibration, mines on the inner wing.

That's a good question and time will tell I suppose. Although my car is shabby I didn't want to drill any holes in it. I also felt if I had mounted the module on the inner wing that the wires would clutter getting to the washer bottle (which in my car is on the inner wing not that I fill it often ). I wonder how many cars other than Morris Minors mounted the coil on the dynamo? Quite a few I suspect. One might assume Lumenition know this especially as they make a bracket to mount the main module with the coil. Perhaps I'll ask Lumenition but of course it's a bit late now because I have cut all the wires too short to mount the system anywhere else! I did ask Lumenition about cutting the wires and the availability of a replacement loom if ever needed and I sent them a picture of the unit installed on the dynamo which they did not remark upon. There is nothing in the instructions for the kit that advises against dynamo mounting.

I have never taken an Optronic main module apart but I would presume that the electronics are smothered in epoxy and hence very vibration resistant.

I am going on Minors on Tour to Holland in May. I will take a set of points and a condenser just in case.....they hardly weigh anything.

Stephen

[les]

It interesting how many keep a set of points handy, that indicates something to me !
How many keep electronic ignition handy if their points fail

[myoldjalopy]

I just keep a spare set of points, Les. Never needed them.........

[oliver90owner]

How many keep electronic ignition handy if their points fail

Now, that is a bit daft, Les - but I like the comedy.

I am considering rebuilding my electronic ignition kit (it got scavenged for bits after I bought my first diesel). It only needed one, or maybe two, switches (fairly sure it was one) to change over between electronic and Kettering systems.

It never failed but was a bit too light-weight for running in excess of 6000rpm (component changes were needed) while maintaining easy starting, as I recall. A bit of a compromise. I suppose I could have extended the change-over to inside the car……. - but I didn’t.

[les]

Glad you saw the funny side, obvious as it was !!

[svenedin]

How many keep electronic ignition handy if their points fail

Now, that is a bit daft, Les - but I like the comedy.

I am considering rebuilding my electronic ignition kit (it got scavenged for bits after I bought my first diesel). It only needed one, or maybe two, switches (fairly sure it was one) to change over between electronic and Kettering systems.

It never failed but was a bit too light-weight for running in excess of 6000rpm (component changes were needed) while maintaining easy starting, as I recall. A bit of a compromise. I suppose I could have extended the change-over to inside the car……. - but I didn’t.

I quite like the idea of being able to change over at the flick of a switch but the problem with this is that it still uses the contact breaker as a trigger switch even in electronic mode. Although in electronic mode there is no arcing of the points and they will last a long time, the heel of the points still wears and the ignition timing will drift. The advantage of a fully electronic system is that there are no points to wear out and the ignition timing should never alter from initial set up. The Optronic is a very clever idea. No physical contact in the distributor, just switching by a beam of infra-red light being interrupted by the blades of the chopper. It is a shame that the system is still so expensive even more than 50 years after it was invented.

Stephen

[svenedin]

I have decided that I am going to move the main module to the inner wing. I mulled over the suggestion of vibration with mounting on the dynamo and it bothers me. Vibration in that location is often blamed for killing ignition coils.

I will play around with potential locations next weekend when I have time. I may put the main module on the inner wing near the front or possibly there is room to hide it under the elephant's trunk heater fresh air intake pipe.

I am impressed so far. The engine runs very well. Less choke and choke for a much shorter time is needed even in this cold weather. Engine performance seems very good or as good as it can be for a totally standard elderly 1098. I went out for a drive on Sunday. Top down with the temperature hovering around freezing and it was a most enjoyable drive and a 5 mile hike with the dog.

Stephen

[svenedin]

Just to finish off this thread, I moved the Optronic power module (PMA-50). It is now on the inner wing underneath the heater fresh air intake pipe. It is discreetly hidden away and cannot really be seen without thorough scrutiny. Yes I know my engine bay needs stripping and painting.......

Stephen

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[svenedin]

I thought I would add to this thread that I started 2 1/2 years ago.

The Optronic worked flawlessly until a recent trip to France. I was very pleased with it. Basically fit and forget.

Without repeating a long story (which I wrote about in another thread) I had a lot of ignition problems and broke down 3 times. Although I had an accurate multimeter and quite a few tools with me, it is never the same as in the comfort of a garage at home trying to diagnose a problem when broken down. During the trip I switched back to using points and the car ran well enough that way, except for a failed condenser which I put down to bad luck.

On retuning home, I diagnosed the problem to a very worn out ignition switch. 57 years old (it was date stamped). The switch had a high resistance in the run position of between 2 and 5 ohms depending on how the ignition key was jiggled. I replaced the switch and everything was back to normal. The Optronic worked flawlessly again and had suffered no ill effects.

The symptoms we had were that the car started easily, ran as if nothing whatsoever was wrong for about 5-10 minutes driving and then the engine would feel rough and sluggish to accelerate with a lack of power. Now that I know that the ignition switch was at fault, it seems reasonable to assume that the electronic ignition tolerated the resistance in the switch cold but that as the switch heated up with that resistance, the resistance increased to the point that the electronic ignition received insufficient voltage and stopped working properly and eventually would not work at all with the engine cutting out. Although I fiddled with all of the ignition components (coil, rotor, HT leads, distributor cap) and thought I had fixed the fault I suspect the engine would have restarted anyway once the ignition switch had cooled down. The other thing that happened was that the coil got extremely hot. They do get hot anyway and the weather was 35 C every day but one coil did fail completely. Whether this was due to the poor quality of modern coils or that the malfunctioning electronic ignition (due to under voltage) was giving an excessive dwell time I really do not know. We did smell a burning electrical smell several times but my car is a convertible and we had the top down all the time; there are lots of smells when driving around that are nothing to do with the car. On reflection, this was the ignition switch cooking itself.

So the summary of this ramble is that high quality electronic ignition such as Optronic can be superb but they are not tolerant of electrical problems. Points will get you home when an electronic ignition system has given up. I have now changed my thinking to a view that points are the more robust system providing of course they are gapped and maintained properly. The other thing I have learned is not to get fixated with what is under the bonnet and to remember that the ignition system is a complete circuit that includes the ignition switch.

A learning point would be that it is highly inadvisable to change from a poorly operating points system to electronic ignition. The car should be running well on points and the electrical system checked before considering changing to electronic ignition. It just will not tolerate abnormal resistances, under voltage etc. No harm seems to result from under powering an electronic ignition, it just does not work properly until the fault is rectified. On the other hand, over voltage such as a faulty dynamo/alternator regulator will destroy the electronics.

Always carry points, condenser, the screws needed and the low tension terminal. Remember the tools to re-fit the points including a feeler gauge. Then you can get yourself out of trouble. We never once called the recovery service.

Stephen

[Mervin]

"How many keep electronic ignition handy if their points fail "
Guilty of the opposite Les. I fitted a Powerspark +ve earth electronic replacement to my distributor. For +ve earth it does require some wiring alterations.
I carried a spare points distributor around just in case! However, if the electronic ign. failed, the wiring would need to revert to original for fitting the points dist'r. I didn't want to do this if stuck on the road somewhere.
I decided to have the Distributor Dr. treatment on the spare/emergency distributor and fitted that. Rather than a complete distributor, I now carry D.Dr. points, rotor arm, condensor, cap and internal l.t. lead.

[svenedin]

"How many keep electronic ignition handy if their points fail "
Guilty of the opposite Les. I fitted a Powerspark +ve earth electronic replacement to my distributor. For +ve earth it does require some wiring alterations.
I carried a spare points distributor around just in case! However, if the electronic ign. failed, the wiring would need to revert to original for fitting the points dist'r. I didn't want to do this if stuck on the road somewhere.
I decided to have the Distributor Dr. treatment on the spare/emergency distributor and fitted that. Rather than a complete distributor, I now carry D.Dr. points, rotor arm, condensor, cap and internal l.t. lead.

Yes there are some small wiring changes needed if changing from POS earth electronic ignition back to points. This actually caused me a load of trouble even though it should be very simple. I believe that ring terminals are more secure and less likely to make a bad contact to the coil so with my electronic ignition set up I had the leads connected to the coil with ring terminals and I had never fitted the spade terminals to the coil. When I decided to revert back to points in an urgent situation overseas, I found I could not connect the ignition white wire or distributor low tension black/white wire to the coil . It wasn't actually that funny at the time broken down in 35 C heat. I had a selection of crimp fittings and some wire in the car and managed a working bodge until another participant on Minors on Tour gave me some coil terminals a few days later.

Stephen