The MGA With An Attitude

At 04:57 PM 6/27/04 -0400, someone remaining anonymous wrote:
>"I am considering putting an electronic ignition system in my MGA.... It doesn't seem to be that should I take the plunge or not?"

This has been around enough times, so I suppose I should put my $.02 in and posted it. There are pros and cons, and a lot of people get caught up in the pros without due consideration of the cons. This can lead to unexpected (and undesirable) consequences.

On the pro side, the reasons most people give for installing electronic ignition is to reduce maintenance and to increase reliability by eliminating the contact points. This can be true, up to a certain point. To the extent that you might "expect" the electronic module to run forever with no problems, the periodic maintenance for adjusting and replacing points is eliminated. Also the likelihood of being inconvenienced by some roadside stop for attention to the points is reduced. In fact on any given single driving day the electronic module may be more likely to be trouble free. If that is what you had in mind, then it may be worth the purchase price, and the time required for installation. But that its not the whole story.

On the con side, both the maintenance and reliability issues can be questioned, and the original cost of installation may not ever be economically justified. My most important consideration about reliability is how likely it is that I will be able to continue driving to the end of the day every day, and to always get the car home without needing a tow or some outside service assistance. A little occasional fiddling with points does not hurt that goal. A spare set of contact points is really cheap and small and fits easily in my traveling tool kit, so in nearly a million miles of driving with contact points in the distributor on various cars I have never been stranded on the roadside (at least not for more than a few minutes).

I have known a large number of cars to be dead on the roadside with failed electronic ignition units. There is no guarantee that they will last forever without failure, and in fact they may fail more often than many people would like to admit or think about. The likelihood of being able to drive the rest of your life without ever having a failure of the electronic ignition module might be better than 50/50, but maybe not if you drive a lot.

Virtually every electronic ignition module has two things in common. They contain a coil of very fine enameled copper wire, and they are encapsulated in molded plastic. Over time the thin insulation on the wire tends to break down causing shorts between windings, and occasionally the thin wire may corrode and break. The plastic goes brittle with age and can eventually crack, leaving an open path for a short to ground (especially in damp conditions). All of these failure modes are aggravated by vibration and heat. For these reasons a reasonable life expectancy for any electronic module might be about 10 years or 100,000 miles, whichever comes first (it could fail earlier or later). After that the likelihood of failure jumps dramatically, so you might consider the cost and time for replacing the unit about that often as part of periodic maintenance.

The important point is to consider the consequences, what happens WHEN the electronic unit does fail on the road? It is against my morals to carry either a cell phone or an auto club card when traveling. [Okay, as of 2014 I now have a cell phone, because it is my only phone]. If my car has a problem, I want to be able to fix it and drive on, not wait for roadside assistance or towing or parts delivery for possible repairs. To that end, if you run electronic ignition in your car you should at all times carry a spare electronic module (double the purchase cost) or the parts to convert it back to the original points installation in case of electronic failure. The electronic modules used in MGs are not a part that you can pick up from stock at just any local auto parts store. These units are usually special order.

From a cost basis, a lifetime supply of contact points will never be as expensive as one electronic ignition module. From a labor basis, the time to order and install the electronic module, including reading and understanding instructions and getting it right and testing after installation, may exceed the time required to install and service contact points for the next 10 years. The cost and/or inconvenience of just one roadside failure of the electronic module in your entire lifetime may outweigh all of the advantages combined.

The summary result of all this is that the cost for installation of the electronic module has the effect of transferring some labor time (or labor cost) to a different place and time. In effect you are buying with your money the effect of "slightly" reducing the overall daily and periodic maintenance of the vehicle, for which you incur possibly more labor time and cost up front for the installation of the electronic module. You may also incur more labor time and cost later on (with a totally unpredictable time of occurrence) if the module should ever fail. Furthermore, it is not uncommon to accidentally fry the new electronic module during initial installation before it ever hits the road. Also the electronic module might be fried later on if someone accidentally reverses electrical polarity, such as installing a battery backward. It only takes a momentary contact in wrong polarity to blow out some electronic parts.

The net result of this accounting is that the electronic ignition will always be more expensive (as a whole) than maintaining the original contact points setup, both in the cost of parts and in labor time. And you need to be constantly prepared to handle a failure of the electronic module at any time in any place (which will never be convenient). For me the few minutes per year that it takes to do points maintenance is not much of an issue when it is done along with other required periodic maintenance, such as changing the oil filter. When points are properly maintained with normal periodic maintenance, there is seldom any problem with them on the road. This means you get to do this little bit of work at your convenience in your home shop. And the incidence of having any problem at all with points while traveling may be less often than failure of an electronic ignition module.

The only other issue I know with points is drift of dwell and spark timing. As the contacts and rubbing foot wear wear slowly with normal use the dwell and timing changes slightly. This demands some periodic adjustment of the contact points, which time is included in the notes above. As long as the points are properly maintained, the amount of drift in dwell and timing will be inconsequential.

Truth be known, electronic ignition is like "Maintenance for Dummies". It is good for those people who want to ignore the car until it stops running, don't mind paying the bill for the installation, and don't mind paying the bill for the consequences of a failure. This is exactly why all new cars have electronic ignition, and lots of other parts related to emissions control. It is long recognized by the government that many people will neglect maintenance of the vehicle as long as it keeps running. So the emissions controls are designed to keep the exhaust clean in spite of such neglect, as long as the engine is running. It is of little consequence to emissions if the engine quits running. To that end emissions controls on new cars are mandated by law to be covered by warranty for 50,000 miles, after which the owner will be stuck with any future repair cost and any inconvenience caused by failure.

On the other hand, if I could buy two electronic ignition modules for under $50 total (or even one for $25), I might be tempted to give it a try (once). Even then if an electronic module should ever fail on the road, I don't suppose I would ever buy the replacement for it.

$.02, -- Barney Gaylord

On July 31, 2014, Jeff Schlemmer of Advanced Distributors in Minnesota, USA wrote:
"There are many, many downfalls to electronic ignition in a car with spark plug wires. The only benefit is that it hides a couple problems caused by wear and eliminates the need to adjust points. Properly fixing the distributor will make your car run better than masking issues with electronics. I have seen issues on the dyno with RFI noise ALWAYS affecting the ignition signal when using electronic ignitions. You don't see that with points, which typically means 4-7 hp gains when using points".

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