Welcome to our resource for MG Car Information.



MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Electronic ignition - my mind's made up

My Roadster refused to start after a drive a few weeks ago. I turned the key and the starter span and span without the hint of the engine catching. I tried again and it caught instantly. Then over the weekend it died at a junction. This time it took 10 long minutes before I could restart it.

There was no spark and the most frustrating thing was knowing there was not a thing I could do to remedy things thanks to the solid state black box (Newtronic) I'd installed for the ignition.

I'm resolute now as it's a case of twice bitten once shy for me. I got rid of the Lumenition system on my GT a couple of years ago after, very embarrassingly, it refused to start to be moved off the MoT tester's ramps having just passed the test. An afternoon spent stubbornly attempting to diagnose things in full view of the chuckling mechanics (it would run for 10 seconds before dying) left me walking home but when I returned that night with full tool kit and helpers it started first time and took another week to link the problem to the Lumenition.

So it's all clockwork and points for me. I think I'm becoming a Lucas disciple and I'm sorry, Master, for ever doubting you!
Steve Postins

Hi, Steve:

Sorry to hear about your ignition problems. FWIW, I installed a pertronix electronic system in my 69 MGB shortly after I got it 4 years ago. It was a no brainer to install and I haven't had any hint of ignition problems.
T.R. Fisher

I did have a Pertonix failure, but it runs soooo nice with it.
Perhaps when the 'kinks' are worked out, electronic's are far superior to points/condensor.

DCM McCullough

I have a Crane electronic ignition that has never failed in many years. But that's because I carry insurance in the form of a spare distributor with points, 7/16 wrench for the distributor removal, and a light bulb with wires for setting the timing.
werner haussmann

I've run aftermarket electronic ignitions since the 1970's. I had one break down in the late 70's.

Modern cars are all electronic. They are very reliable.

Points are dramatically less reliable and produce a poorer spark.

The only advantage is that the replacement part (points) are cheap small and relatively easy to replace.

Points change timing as they wear. Points produce inconsistent timing and dwell if you have any wobble in that heritage distributor shaft. Points need to be filed and adjusted periodically. That adjustment includes resetting the timing.

However, If you are still silly enough to be driving a 1960's automobile, you are probably eager to experience the complete heritage and relive the bad as well as the good of the past.

Barry Parkinson

In Steve's defence, the only time I have ever been totally stranded due to an ignition failure, was in a modern car with electronic ignition. I will concede that modern electronic ignitions are extremely reliable and a much better method of igniting the fuel/air charge in a cylinder, however, when they die, all you can do is wait for AAA to come to the rescue, whereas I have always been able to get home with the old archaic points system, however inefficient it may be. that said, I have installed a Pertronix ignition in our MGB and am quite pleased with it, but if one looks throught he spares that I carry, they will find a backup distributor base plate complete with preset points installed, just in case...
Cheers - Dave
David DuBois

Steve. Glad you were able to troubleshoot the problem and get the car back on the road. As to the old points vs. electronic points replacment system, I can definitely state that it is easier to write "points" than "electronic points replacement system" when typing up a post. Beyond that, I have come to the conclusion that there are advantages and disadvantages associated with each system and, anyone, such as yourself, who is competent to trouble shoot the problem and correct it is fully competent to make the proper, personal, choice.

My standard rant: Regardless of coil triggering system, the basic distributor is a 30+ year old system and needs to be cleaned, inspected and lubricated on a regular basis (annually for daily drivers and biannually for pleasure cars). Take good care of the basic distributor if you want it to work properly with either system.

Again, glad you got the problem sorted and thanks for letting us know.

Les Bengtson

I have the Petronix Ignitor (sold in the UK as Aldon Ignitor) system fitted to my daily driver car for five years now and I am very pleased with its performance.

I wouldn't go back to points even if the electronic ignition were to fail, I'd buy another no question. Aside form the reduced maintenance I get improved starting and smoother running. Frequent adjustment of points gap/dwell angle, damp problems, condensor failure etc, etc. No thanks!


15 years using the Pertronix Ignitor. Never failed...

Ray 1977mgb

change the lot new dizzy for standard cam aldon 101by2 and a aldon ignitor ,no fancy coils and amps .£120

I am sorry to hear of the ignition woes but I cannot help thinking the problem is not with the electronic igintion per se but more that particular unit and it seems to me to be silly to condemn them all on that basis.

I ran an electronic ignition for years and never had any problem but then I rarely had problems with any of my cars anyway since the preventative maintenance aspect was well taken care of. It was a Crane unit and was fitted against all "expert" advice along the usual lines..."if the factory thought they were so good they would have fitted one" and so on.

Around the same time many of my friends fitted the Luminition products and had nothing but problems and these were in my opinion anyway cheap junk and factory fitting made them factory fitted cheap junk.

Incidently the reason most car makers went over to electronic ignitions were for reasons of reliability and consistency in performance over the points type not for any performance gain.

Some thoughts.

Peter Thomas

I took Dave's advice. I use a petronix, but carry a fully set up plate. Only takes a few minutes to swap them out.
Bruce Cunha

I agree with the use of electronic ignitions, but have never heard of the Newtronic brand. I have used Crane and Pertronix and the only problem I have ever encountered since my first install in 1987 was a cut wire, which was entirely my fault.
Yes, its a good idea to carry a spare points plate that's ready to install. I highly recommend it, but don't do it myself. I always figure that the spares you have with you won't ever be the ones you actually need! Pessimistic? A little...
Jeff Schlemmer

Jeff - Following your line of thought, It becomes very easyto make our cars 100% reliable - just carry one of everything in the car, then nothing will ever breakdown ;) Dave
David DuBois

I've had points go bad numerous times. Yea I should have checked earlier. Condensers go out - suddenly and unexpectedly - bam! the engine just quits. I've had to adjust and file points when the engine suddenly started running like crap or wouldn't start. On an old distributor with loose bushings and dual points and because of the wobble, I could only get the engine to run with one set of points at one clearance and the other set at a different setting.

We like points because we can look at them and see what they do.

I've seen what they can do and I'm not going back to points.

The big issue I am encountering is the inadequacy of the stock MGB distributor for a true hi voltage ignition system.

I've had the spark jump across the rotor to the distributor shaft and, in effect, shut down the ignition system. Jump from one plug wire across the outside of a wet dist cap down to the distributor body and shut down 1 cylinder.

With a hot coil and good transistor switch you can have the system produce voltages and spark distances that easily jump the gap inside and outside the distributor. The ignition system only reaches the voltage necessary to bridge the gap and get a spark. With a fouled plug or poor plug wire, that voltage can get too high for the system.

Higher compression and supercharging increase the resistance to spark. Thicker compressed air is a better insulator than less compressed air. I've run .090" spark plug gap and the system worked when all was in good order. I didn't notice any meaningful difference in driveability beyond .050" gap though.

I would like a centrifugal and vacuum advance ignition with a larger distributor cap and rotor to provide extra distance to stop errant sparks. It should also have adjustable advance curves for both rpm and gross amount of advance. And an adjustable vacuum advance to be used for daily driving. Mallory seems to be the only company making such for the MGB.

Barry Parkinson

I am thinking of putting the EDIS electronic ignition in my 'B'. I have heard good reports about them and I can still leave the Dizzy in as a precaution!
Eric Martin

Thanks for all the comments. I know Iím being harsh condemning these (aftermarket) systems so squarely but even on balance I have to give them the thumbs down. Here's my rationale.

Firstly, electronic ignition has been the only item that's prevented me from getting home in my GT. OK, that's not rational, that's wounded pride but all the same.

Secondly, the cars seem to run the same to me, with or without, so I don't feel I'm getting a performance gain.

Finally, I learnt to carry a spare baseplate one when the Lumentition went bad on my other car, but had left it and a couple of other bits I'll no doubt soon need, in my other car. So I can confirm Jeff's theory. If I could have found the baseplate, what hit me with crystal clarity when I stalled at the junction was that I was going to have to change out all of the electronics simply to be in a position to start troubleshooting. I could just about remember how to untangle the wiring, but having removed the dizzy, reinstalled the baseplate, reconnected the wiring and replaced the dizzy, I would still be left with the timing to set. So it would have to be out with a spark plug, hold it against the block, tug on the fan belt, look (hope) for a spark, adjust, try again.... and all this would be done to a background of tooting horns and Anglo-Saxon sign language. Then having got it all back to its original state, I could start to look for the fault, which could have gone, or might still have been there, or could have been "fixed" by all the disturbance only to reappear the next time I took the car out.

In the event I elected to think negative thoughts about the black box until it succumbed and let me drive home, at which point I pulled it out by the roots.
Steve Postins

Judging by some of the comments some people fitted electronic ignition along time ago. Although they may not be on the same units now.

I fitted Mobelec Magnum electronic ignition to my previous MGB in 1981. Its a brand no longer available. When I changed my B in 1992 for the current one I transferred it over.

By my reconning it must be on borrowed time. So one day I will get around to sorting myself out a spare base plate or distributer ready set up. The big question is will I sort out the spare in time.

If it was not for the MGCC rules in standard class sprint and hill climb here in the UK I would go for the MegaJolt/Edis type multi coil set up and get rid of the distributor all together.

David Witham

Check the supercharging web site, there is much discussion regarding an electronic ignition with the timer plate on the front pulley.
Barry Parkinson

I threw my Pirahna off the car about 5 years ago when it was so down on energy that high speed misfire meant I had to let a turbo metro get away on track day. This memory still hurts today.
Stan Best

Under "Hotlines" my June 2006 issue of "Enjoying MG" (MGOC) shows, on page 9, the "123 Electronic Ignition Distributor" with adjustable advance curves. Is this distributor the answer to our prayers?

Despite three Crane-Allison failures over the years, I am currently running Pertronix on my '73 GT, along with MSD ignition. So far, knock on wood... I do have that spare base plate and points in the tool kit at all times! John Twist used to say "electronic ignitions are pointless" but with the advant of MSD, he changed his tune. That convinced me. I think the MSD is helping but I haven't dared open the gaps much, figuring the spark might find a more attractive route to ground somewhere else in the system.

Allen Bachelder

Barry, if you don't care about stock appearances, Davis Unified Ignition (D.U.I.) has the distributor for you! They convert a Pontiac 4 cyl HEI distributor to fit the B. Theoretically, its a very easy task and you could probably do it, if you have a lathe. It has a much larger distributor cap, it is electronic, parts are cheap, and you can get it set up HOT for under $100.

By the way, my Crane ignition is still working even after I welded the distributor cap clip to the Mini-starter battery terminal a couple days ago!
Jeff Schlemmer

Barry, I forgot to mention that the adjustable vacuum advance for that distributor is under $20.
Jeff Schlemmer

The only real trouble I have had with my 64 MGB has been caused by distributor failure. After the engine died twice in a couple of months, I thought hard about converting to electronic ignition, but for some reason ended up by replacing the old 25D with a new repro 45D distributor.

What a difference! The engine was so smooth it almost felt like a six cylinder compared to the way it ran before. I also find it will now run for a veeery long time before I have to adjust the points.

Of course electronic ignition is technically superior to the old points system, but it is not fair to condemn points ignition when the real reason for trouble often is a wobbling, worn out distributor.

To me, honest mechanical simplicity is one of the beauties of the MGB. So I stick to points!

For those of you who fear the failure of the inscrutable electronic ignition, the dwell extender may be the answer. It is a diode and a capacitor. It is one wire that you connect to the points and immediately upon the points opening it closes the circuit resulting in a longer dwell period for the coil to charge. It also stops all burning of the points. The points will go many thousand miles with no adjustment. If it quits just cut the wire and you are back to your stock system.

Radio shack used to sell kits. I searched the web a year or two ago and found plans to make your own and a year or two ago I was in a used tool shop and saw a dwell extender in a display case. The parts are less than $10.

Back in the '70's I had a type 3 Karman Ghia VW with a modified engine that I put many miles on. The points kept frying with a hot coil. The dwell extender took care of the problem.

Barry Parkinson

This thread was discussed between 05/06/2006 and 07/06/2006

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.