Earlier this year Daniel Stern wrote an article that looked at General Motor’s HEI ignition system. The GM HEI ignition is well known among car enthusiasts, but it was far from the first attempt at electronic ignition by an American auto maker. Throughout the 1960’s GM, Ford and Chrysler all experimented with different versions of electronic ignitions, or as they were commonly known then, transistorized (or just transistor) ignition. Just as the transistor revolutionized radios, it did the same with automobile ignitions. Nevertheless, the road to a modern electronic ignition was a storied one. This three part series will examine the evolution of electronic ignitions used by American manufacturers from the 1960s until they became the industry standard in the 1970s.
Before we go into detail on the electronic ignition, it’s important to go over the basics of how a breaker-point operated inductive ignition system works. What exactly is that mouthful? This is just a big elaborate name for the breaker-point ignition system that most cars used up until the 1970s. A breaker-point ignition system is comprised of several key components. These include the distributor, the ignition coil, a resistor (either a ballast or resistor wire), the spark plug wires and of course the spark plugs. The ignition has a primary and secondary circuit. These two circuits meet inside the ignition coil. A coil, which is pulse transformer, consists of primary and secondary windings. The primary windings have about 200 to 300 turns of larger wire, while the secondary windings have about 20,000 to 30,000 turns of very fine wire. In the center of the coil is an iron core.
So how does it all work? When the breaker points in the distributor are closed, the current from the battery flows through a resistor which reduces the voltage from 12 volts to approximately 8 volts. These 8 volts go through the primary windings on the ignition coil then through the closed breaker points and finally to ground, completing the circuit. When the points are closed there is no spark at the spark plug.
It is important to remember that when electrical current flows through the primary windings in the coil, it creates a magnetic field. So when the breaker points open, there is no longer a direct connection for the current to flow to ground. This causes the magnetic field in the coil to collapse very rapidly. The magnetic flux lines cross from the primary to the secondary windings, and this induces a much higher voltage (about 25,000 volts) into the secondary windings. The high voltage current induced in the secondary windings (about 25,000 volts) flows from the coil to the distributor. The distributor then routes the current to the correct spark plug wire and produces the ignition spark at the spark plug.
It should be noted that the time to charge a coil to full saturation (dwell time) is fixed. However, as engine RPM increases, the time between the points opening and closing is reduced. This means at higher RPM, the coil does not have enough time to become fully saturated. This results in a reduced ignition output, as the lower primary voltage, creates a lower secondary voltage. Some manufacturers got around this by using dual points, which increased the dwell time at higher RPM.
The basic breaker points ignition system works reasonable well, but it does have a number of serious limitations. Firstly, the current must all pass through the breaker points. To obtain reasonable life out of a set of points, the amperage must be limited, typically to somewhere around 3.5-4.0 amps. Increasing the current beyond these levels causes a rapid degradation of the breaker point life. This is the reason why the voltage is reduced to about 8 volts by a ballast resistor or resistor wire (the current is reduced along with the voltage). This reduced power allows for a reasonable compromise for breaker point life and ignition energy. The only exception is when the engine is starting the resistor is bypassed while the starter is engaged. This allows a full 12 volts to be delivered for the coil for maximum ignition energy. This brief period doesn’t have a major effect on points wear. Secondly, each time the breaker points open and close, the arcing that occurs causes point wear. In addition, the rubbing block on the distributor also wears. This wear slowly reduces the accuracy of the points over time, hence the need for frequent tune-ups. Finally, high RPM use causes “point bounce” which can cause misfires and poor ignition performance.
Due to the limitations and the high maintenance of points ignitions, in the early 1960’s American auto manufacturers started to look at ignition solutions that used transistors in place of the points. The use of transistors for the switching mechanism had the potential to be a much faster and more efficient the rather basic mechanical breaker points switch. General Motors and Ford were the first of the big three to experiment with a transistorized ignition with both having systems available for the 1963 model year.
Ford offered a transistorized ignition system on the Ford Thunderbird and 427 powered vehicles for the 1963 model year. This system was the most basic form of electronic ignition and it actually still used a set of breaker points. So, exactly how does an electronic system with a set of points actually offer any improvements? Well, the points remained in the ignition as the trigger for the coil, however, they were now essentially used like a relay.
A relay allows a low current circuit to trigger a higher current circuit. You can use a switch on a low current circuit and connect it to a high current circuit through a relay. Once that switch closes, the relay will “trigger” the high current circuit. Consequently, a relay allows a switch with low current to control a high current circuit without having the high current flowing through it. For the Ford transistor ignition, the breakers points were like that low current switch.
The Ford transistor ignition added a new device called the amplifier. An amplifier is just an old name for an ignition module and it contained the super-fast switching transistors inside. The amplifier is connected between the ignition switch (power supply) and the ignition coil, and that supplies the power to the coil. It is the “master switch” and controls when the coil is in saturation or collapse. Basically it does the job of the points in a conventional ignition.
The way it works is the points are used to trigger the amplifier. The amplifier does not know when to switch the coil from saturation to collapse. This job remains that of the breaker points and the rubbing block. The breaker points still open and close based on the distributor rotor’s location. When the points open, this triggers the amplifier which will use transistors to open the primary circuit between the coil and ground. This causes the secondary circuit be induced, and the spark plug will fire. Since the breaker points are no longer supplying power to the coil, Ford reduced the voltage to 3 volts (which also reduces the current) through the use of a resistor. The low voltage significantly reduced the points wear resulting in a substantially longer point life. This means the points will be more accurate for a longer time and require less adjustment. The amplifier allowed for an increase in primary circuit voltage and faster switching of the coil, which increases the ignition’s energy and high RPM performance.
Despite the lower maintenance requirements and greater overall ignition energy, the Ford transistor ignition was not a popular option. It remained standard on the 427 until 1967, but didn’t even last that long on the Thunderbird option list leaving after 1966. I explained the basics of the Ford Transistor ignition above, but it was actually a fair bit more complex, as Ford also incorporated a cold start mode. While it may have been somewhat beneficial to a person racing a 427 Ford, to the average owner the lower maintenance was probably the only big advantage. However, this rather costly option was far more complex than a conventional ignition and when it did break, it was far more costly and difficult to repair.
The Delco-Remy division began to design a new ignition system around 1962 with the goals to improve reliability, increase component life, and require less maintenance. The result was the Delcotronic Transistor Controlled Magnetic Pulse Ignition. This Delco transistor ignition was very advanced for its day and unlike the Ford system, it completely eliminated the breaker points from the distributor. Instead of a rubbing block which open and closed a set of mechanical points, this new ignition system used a magnetic pulse generator (magnetic pickup) inside the distributor to trigger the transistors in the amplifier. An iron timer core replaces the rubbing block and it has the same number of equally spaced projections (or vanes) as the engine has cylinders. The pickup assembly has a ceramic permanent magnet, a stationary pole piece and the pickup coil. The stationary pole piece also has equally spaced teeth, one for each cylinder.
As the distributor shaft rotates and the teeth of the stationary pole piece and the timer core approach alignment, the output voltage increases as positive polarity. As the teeth pass through alignment, the output voltage abruptly reverses and passes through zero to produce a negative polarity. As the voltage crosses the zero point, it signals the amplifier to turn off the coil’s primary current, which induces the secondary circuit and fires the spark plug. This voltage signal that is being created is really just a small AC current. The amplifier’s solid state technology determines when to turn the primary circuit back on. And as the teeth on timer core and pole piece move further away, a positive voltage is created again, stating the cycle over. The pickup coil’s signal provides a highly accurate switching point for accurate spark timing that is not affected by temperature or vibration.
Unlike the Ford system, this ignition had no mechanical parts to wear out. The use of a magnetic pulse generator to trigger the amplifier was a big step forward towards modern electronic ignition that most electronic distributor based systems would eventually adopt. Delco-Remy offered this ignition as an aftermarket conversion kit as well, but the kit used breaker points to trigger the amplifier box, and it operated just like the Ford system. This made the system less costly and much simpler to install as the old distributor could be reused.
The Delco transistor ignition was first introduced as an option for Pontiac in 1963 on the 389 and 421 engines. It was added to the option list for Corvette in 1964 under the option code K66. It was available on other high-performance Chevrolets during the 1960s but it was most commonly found on Corvettes. It was the most common early electronic ignition. Although a complex and expensive ignition, the Delco system was an excellent ignition for high-RPM engines and was mandatory on several high performance engines. Racers and high performance enthusiast frequently used or retrofitted this ignition because it performed so well. 1971 was the last year the Delco transistor ignition was available, last being used on the Chevrolet LT1 and LS6 high performance engines. However, it too was plagued with the similar low cost-benefit of the Ford ignition, offer few big advantages for the average driver, while being more costly, far more complex in design and much more difficult to repair.
Although Chrysler would be the first of the big three to adopt electronic ignition across its vehicle line in 1973, it didn’t have much to offer prior to that. In 1966, Dodge offered a Motorola Transistor ignition system for its fleet models only. The big appeal of transistor ignition for fleet operators in was the reduced maintenance costs. Motorola’s ignition was an aftermarket system, it was designed to be easily retrofitted to other cars. So, like the Ford system and the add-on Delco system, the Motorola system also used points to trigger an amplifier box and functioned in the same manner.
These earliest versions of electronic ignition had some of all of the following objectives: Higher secondary (spark plug) voltage, reduced maintenance and better high speed operation. Ford and General Motors used these ignitions on high performance vehicles, in particular the high RPM engines. This is where the transistor ignition had a clear advantage over the typical breaker-points setup, with the fast switch transistors allowing for more coil saturation time. Dodge, on the other hand, offered the transistor ignition for fleet use only which was obviously an attempt at reducing maintenance costs rather than increase high RPM performance.
Although these electronic ignitions offered improvement as over breaker points ignitions, there were a number of significant drawbacks. The cost of the ignition system was far higher, there were more components, they required specialized parts such as special ignition coils, and they were far more complex. The complexity meant that fixing these systems was required more skill and knowledge. And if the system did fail, it usually did so suddenly, and parts were often not readily available.
In the next installment I will continue to cover some additional early electronic ignition systems and the first mainstream electronic ignitions used by the Big Three.
A special thanks to Daniel Stern for supplying some of the research material on vintage ignition systems.
Automotive History: Electronic Ignition – Losing the Points, Part 2
Automotive History: Electronic Ignition – Losing the Points, Part 3
What an amazing piece of work. I am really looking forward to the next installment. I learned a lot from this article, and many thanks, Vince!
You refer to the Big 3, but what about AMC, weren’t they doing anything in the 60’s to circumvent mechanical ignition?
Fascinating and informative … even though the sixties were my decade of gaining automotive awareness, I didn’t realize that electronic ignitions were available before the seventies. One minor semantic nit: I’d argue that the primary and secondary circuits aren’t really connected in the coil, though I guess in modern parlance it’s a wireless “connection”. I still have feeler gauges, useful for valve clearance as well as point clearance, though as I recall a match book cover worked in a pinch. I also have a few point files and two sets of ignition wrenches (SAE and metric) but my dwell-tach as well as my timing light disappeared a while ago.
Thanks for the feedback. I see you point that my wording is somewhat unclear and it makes it seems as though the primary and secondary circuits are physically connected – which obviously they are not. I reworded it and I think it makes it more clear if you read the article as a whole.
Yes the primary and secondary windings are not connected, they are magnetically coupled.
On “most” ignition coils, the primary and secondary windings ARE electrically connected.
This is easily verified with an ohmmeter–with one lead on either the primary + or – connection, and the other lead in the secondary “coil wire” terminal, you’ll read continuity. It’s how you’re told to read the “secondary resistance” in the service manual.
Some HEI in-cap ignition coils have electrically-separated primary and secondary windings. (“four-terminal coils” having a black wire) There may be others.
A fascinating read. I love these “beginnings of” pieces.
It may be coming, but Studebaker was right behind Ford and GM with a transistorized ignition system announced in 1963. It was built by Prestolite and there are undated press release photos from 1963. The 1964 brochure says that it was available in the “Jet Thrust” engines – optional on the R1 and R2 and standard on the R3 and R4.
It was available across the line in 65 and 66 models, even as a no-cost option on the 65-66 Daytona. From what I can tell it was much like the Ford system in that it still used breaker points (dual points in the 1964 Jet Thrust engines). I don’t think they were commonly seen but they surely helped that Avanti set the speed record in late 1963.
The back side of the press release photo.
Thanks for the great info JP. It seems the Studebaker used an aftermarket system, like Dodge did with the Motorola. It appears to be a points triggered system like you already deduced. Of the earliest systems it seems that Delco-Remy was the only one with a magnetic pulse style distributor. This series won’t really look at the independents, I just focused on the Big 3 who did most of the innovation. AMC would have there own electronic systems too, but they didn’t develop anything in house.
Fascinating stuff, Vince. I’m sometimes flabbergasted to learn how early some of this technology existed, but wasn’t available (or was difficult) in the name of cost-cutting and profitability.
I know this series is intentionally US-biased, but it would be interesting to see a comparison to what Europeans (especially Bosch) were doing along the same timelines.
And maybe you’ll answer this later in the series or maybe the hive mind knows, but was the eventual conversion to across-the-board electronic ignition mostly due to emissions laws and fuel embargoes? I wonder… if those things never forced the hand of automakers, would we still be driving cars with points today?
I believe Lucas had some version of electronic ignition in the 1950’s, but I am not well versed on overseas products. The Delco-Remy systems was pretty state of the art for its day. These were the days when GM was still pretty innovative.
Initially, these ignitions were more focused on high performance, but eventually they became more essential. tightening emission standards in the 1970’s meant that a sloppy points ignition was inadequate. So I yes, emission standards was a big reason why they moved mainstream.
Yes the emissions laws, specifically the durability requirements, IE it stayed running clean between recommended service intervals. With points the rubbing block starts to wear from the get go and that changes the timing, which also changes the fuel requirements. So yeah they had to get rid of the points or set overly short service intervals.
Surprisingly, though VW was a early adoptor of fuel injection, ’68 for air cooled and ’77 for water cooled, VW kept points distributors until the 1980 model year, well behind US manufacturers. The went to a hall effect type ignition at this point.
Exactly…I had a 1980 Scirocco with Bosch K-Jetronic fuel injection but points…A year later the 81’s introduced electronic ignition…I bought an LED conversion kit. It had a slotted disc that fitted over the distrbutor shaft. An LED light was installed below that replaced the points….Worked OK for a while, then started misfiring…Went back to the points….The electronic system in 81 used a Hall magnetic sending unit
Fascinating Piece, Vince! Having only one car (my ’73 LTD) that had one of these Rube Goldberg Ignition Devices (breaker points), I have always been amazed that these types of ignitions even worked at all.
I recall being a little boy when my Dad took his ’68 Impala to a friend equipped with a timing light and such and was fascinated with watching him setting the timing. I remember Dad not being happy with his mistake at this time. He had a tank full of high-test (totally not necessary for a Chevy 307) the day the car was tuned up. It was as if the guy tuned the car by ear, or maybe he used “The Force” or whatever, but from that point (pun not intended) he had to continue to use high-test until the next tune up where he could have the timing set back for regular.
I may be getting ahead of myself anticipating what’s next in this series, but my next car, the ’79 Futura with its 200 Straight Six had a distributor, but it was the simplest of things in that I could even replace it myself! The Rotor and Cap were exactly that, a little rotor with a metal contact, and a cap with 6 metal contacts in a circle separated by 60 degrees, and the coil wire went in the center…. but then there was this little metal box mounted to the inside of the wheel well or fender with wires coming out of it. When it started to fail, it was intermittently weird at first, then it completely died and had to be swapped out. That was the easy part. Paying for the little metal box was expensive, but it never gave me trouble again. I think it was called an ignition module. Electronic ignition’s early days indeed.
As someone a little older I was on up-close and personal terms with my induction timing light and my dwell-tach. Points (and condenser) were just something you did every now and then. I was taught that timing to factory spec was a starting place, then the trick was to advance it little by little until you started to get a knock on acceleration, then back it down just a touch. I dusted off those skills in the 90s when I was driving my 68 Chrysler, but then put my equipment away and have not touched it since.
I think you’re one year older than me, JP… I believe you are the same model year as your avatar, a 1959. I’m a 1960 model year, a few months ahead of when the ’61(s) would’ve come out. ;o)
I think I was like 9 or 10 years old when Dad was having the ’68 Chevy tuned up, and although a fuzzy memory, this is exactly what the guy did! So I suppose with my Dad having a tank full of the high octane go go juice at the time, he was then stuck using the good stuff with his car being tuned that way.
Of course today’s cars are equipped with knock sensors and retard the timing if you put 87 in a car that recommends 93. I’ve often wondered if this works the other way around, though… does the timing automatically advance?
My 2016 Civic has a turbocharged engine. Every time I’ve owned a car with a boosted engine, premium is either recommended or required, due to the higher compression. My owner’s manual says “87 Minimum” for a fuel requirement. I’ve experimented with putting high-test in this car and found that it accelerates quicker, and it gets better mileage when running with greater than 90.5 octane (blended up) in the tank.
It’s probably all in my head, as it is when most folks run high octane when they don’t have to do so. The owners manual for my 4.0L V6 Mustang simply says “Required Fuel 87 Octane”, and that’s all I put in it. The car is normally aspirated, and the one time I accidentally*** put 93 in it, I noticed no difference in performance as I expected.
*** I dropped something at the pump and when I bent over to pick it up, my butt hit the “93” button and the pump wouldn’t let me change it. With having committed to claiming my grocery store’s $1.50 per gallon discount with the points I had accumulated, there was no going back, as cancelling the transaction would’ve meant loosing the gas points. I chalked it up to an experiment. Again, the Mustang does not drive differently with high octane, but the Civic seems to run better.
Your Civic’s reaction to higher octane makes sense. In my old-school experience an advance of timing perked up performance. Advance too far and you got a spark knock. Add higher octane gas and the knock went away and you still had the advanced timing.
Knock sensor engines would seem to me to work like this too. I think many of them recommend 93 but say 87 will work. I suspect they run a bit stronger with the 93, as your Civic seems to.
It depends. Some do (run better), others not. No surprise on Retrostang’s turbo Civic, which undoubtedly has to reduce timing (and probably boost) significantly to run on 87. I’m a bit surprised that the manual doesn’t say “93 recommended”.
Numerous tests have shown that almost all naturally aspirated cars set up to run 87 do not achieve higher power or efficiency if run on higher octane gas. Maybe there’s some exceptions, but the rule is not. Which is of course why it’s a total waste of money to put premium in a car that can’t take advantage of it.
Our TSX is in between, as are a number of modern cars which say “93 recommended”. These cars will definitely achieve higher output and efficiency with 93 than on 87. In the TSX, mileage improves close to 10% with 93. If premium is not priced more than about 10% above regular, I use that. But more often in recent years, the price gap has become significantly more than 10%, so I tank regular unless I’m going to drive it hard and fast on a road trip.
Cars that say “Premium required” will still run safely on 87, but it’s probably best not to bother, as the performance/efficiency drop is likely to be more significant.
My Golf will run just fine on 87 an still has plenty of power. Using Chevron 94 octane it gets better mileage-since 94 contains no ethanol. The actual benefit of using the 94 is about 10%-half from no ethanol and half from better ignition timing.
There is slightly more mid-range torque on 94. I have never had enough road to see if it makes better horsepower.
I think that the Civic SI, which is in a slightly different state of tune than my EX-T with the same engine DOES recommend premium in the owners manual.
Perhaps by saying “87 Minimum” and leaving it at that for my car makes sense, in that Civics in the past have usually sold as commuter pods, and requiring premium would likely be a bad marketing move. They do have a base Civic with a NA 2.0L, and that is what most folks looking for a car for their kid to go to college or whatever would pick.. the low budget option or “poverty spec” as I have seen it referred to on these pages.
As to the decision point at the pump there Paul, I’m with ya… Here in Maryland, the price difference is like 50 to 60 cents per gallon at most places except for member stores like Costco and BJ’s, and the 5% improvement I see in economy for my commute just isn’t worth it most days, or why I might blend up some 90+ octane, splitting the difference.
When going on a trip though, especially to the mountains where I might enjoy a little driving fun, but mostly because those easy highway miles seem to really make a difference in economy, maybe closer to the 10% you cite, I’m inclined to put premium in the tank before setting out on such a trip.
I’m sure the “spend like you’re on vacation” has some effect on my decision at the pump when traveling too. ;o)
I don’t believe any cars that aren’t FFVs have the ability to adjust the timing up from what is optimized for the recommended octane rating. I’m pretty sure that all of the non-FFVs just adjust the timing down from that base line and aren’t designed to adjust up from that setting. So that is why you typically don’t see an improvement from putting higher octane in a car designed for 87 and why you can get away with putting 87 even though it is set up to achieve the best performance and economy with 91.
I’ve run a couple tanks of 93 in my ’18 F150 2.7l Ecoboost and didn’t notice anything different performancewise from running 87 in it.
I remember playing with the timing that way on my ’79 Grand Prix. On that one I remember it having quicker response to the pedal, but I didn’t notice any more power otherwise. My ’03 Avalon doesn’t require high octane, but the manual says it can be used for better performance. It is night and day different in the medium to high rev range, although mileage seems the same. My ’05 Taurus with the flex fuel engine doesn’t require high octane, and it isn’t supposed to make a difference, but at the higher revs it seems to pull better and makes a pleasant growl, like an old four barrel carb. It also does the with E-85 so it does seem to adjust for the higher octane. I always experimented with this in all my generic cars over the years and it never made a difference to them before.
Well your experience is mainly due to the fact that it is a Ford FFV. In the early days of FFVs the cars had a physical fuel composition sensor. All the fuel flowed through the sensor and it would determine the amount of ethanol based on the fuel’s capacitance. That signal was sent to the computer which then used it to determine which algorithm and look up table to use for the fuel and timing or where to fall in between the two if it wasn’t pure gas or summer (full) E85. The problem is the sensor wasn’t cheap. So Ford and GM figured out how to determine the fuel through the use of the oxygen and knock sensor. Since they now had to deal with monitoring the evap system the computer knows when you add fuel to the tank. So on the FFV vehicles when the computer senses that fuel has been added and it runs the fuel learn strategy. Once it has learned the fuel it stores that inferred Ethanol content and like the early cars adjusts the timing and fuel accordingly.
In early knock sensor vehicles the knock sensor just signaled the computer to pull out a fixed amount of timing, and it didn’t learn the fuel. However I’m pretty sure that modern non-FFV cars that have a “recommended” octane of higher than 87 go through a similar fuel learn process but in the case I believe they are adjusting the timing down from that which was determined to be optimum for the higher “recommended” octane. I do not believe that cars that don’t have a recommended octane higher than 87 are set up to advance the timing beyond what was determined to be optimum for 87 unless it is a FFV and even they might not do it if the computer doesn’t determine a higher level of ethanol.
Rick you are getting a little ahead of the series, but I will cover off the Dura Spark system your Fairmont would have used once I get to part III.
As for the using higher fuel octane, Paul is correct when he said it depends. For a modern car to take advantage of the higher octane, it needs an advance map that would allow for it to advance the timing further than what is required for 87 octane. On the contrary, most modern cars that require premium, will now back off the timing if 87 octane is used in its place. I suspect most turbo vehicles today will having timing maps that would allow for more aggressive advance curves with higher octane fuels, which is why many recommend higher octane for better performance.
The big advantage of modern electronics controlling the timing advance curve is that it is dynamic to the fuel used, the load on the engine and other conditions. The ECU can automatically deduce what timing is optimal for those conditions. However, there are obviously built-in limits. If those limits are set for 87 octane, like I suspect most cars that have 87 octane recommended would have, then running 91 will give no significant advantage,
Old cars with distributors had static timing curves, both with the mechanical and vacuum advance. So if a car was setup for 87 octane, running 91 octane would offer no advantage since the curve will not change to take advantage of the extra octane. However, you could re-curve the distributor and alter your base timing to take advantage of this higher octane. This is exactly what many old hot rodders did to cars.
Wow…my Father had a ’73 Ranch Wagon (sibling to the ’73 LTD) which he bought new…but of course the first fuel crisis happened at the end of the year, and he reacted strongly (as many people probably did, as it had never been a problem earlier and it scared many of them. He reacted with both his cars; he actually sold his economy car (’68 Renault R10) because my mother didn’t drive standard transmission and he wanted her to drive a car that got better fuel mileage, so he bought a different small car with automatic.
The other thing he did was with me build a Radio Shack kit electronic ignition for the ’73 Ford. Not sure that it actually improved fuel economy much but it probably lengthened the time needed between tuneups. However, it caused him some embarrassment when our car died just a few miles away from my Grandparents (we lived about 4 hours away at the time) and we had to be picked up…..turned out to be a bad coil. My Dad blamed the electronic ignition and he reverted back to the standard breaker ignition as long as we had the car after that.
Yes, I’m old enough to have done old fashioned breaker point tuneup on my own car…I had a timing light (not the fancy induction clip on but the series inline with spark plug #1) a remote starter switch, dwell/tachometer, and along with the requisite points plugs and condenser after loosening the adjustment screw on the distributor, would adjust the timing. Also would put some of that grease on the distributor lobes, and avoid getting it on the points. Every other tuneup I would file down the point surfaces instead of replacing them….had an ignition kit in my Sears toolkit that I got as a Christmas gift one year. Got me through my undergraduate years with that car, except for the blizzard of ’78, where it was always parked outside my parent’s house in Vermont (I was a commuter student…and to jobs when I was working). Now I can’t even find any distributor on my 19 year old car (though I still replace the plugs every so often, mostly to keep them from seizing in the engine).
Interesting timing (no pun intended)…my Dad had a ’73 Country Sedan wagon with the 400, which in the fuel shortage of ’73 decided to build one of those Radio Shack Electronic Ignition kits…I helped him; it was probably the first time I ever soldered anything. However, the electronic Ignition ended up being bypassed when shortly after installation upon a trip to our relatives in Pennsylvania, the car stalled out on I81, and we had to be picked up by relatives…turned out the ignition coil went, and my Dad blamed the electronic ignition….eventually it was yanked (I still have the heatsink box somewhere).
I owned 2 cars with points, my ’74 Datsun 710 and my ’78 Scirocco…but only remember tuneups on the Datsun…I had remote starter switch, dwell/tach, and one of the cheap timing lights that had to go inline with first spark plug. Tried not to put too much grease on the distributor cam lobe lest it go flying off and get into the point contact….I also had a special narrow point file and the little feeler gages to measure the gap later on…as a Christmas present 40 years ago (Dec 1979) my Dad got me a Craftsman tool kit, which included these in an ignition tuneup kit..which I still have…but of course haven’t done a regular tuneup in years…or had to file down points. After the Scirocco I had an ’86 GTi, which had electronic ignition, as have my succeeding cars (really only one other car, my current 2000 Golf…I’ve only owned 5 cars in my 45 years of driving).
That Craftsman tool kit was my most useful gift received ever…still the core of my now expanded tool collection; use it all the time (not just for cars either).
Excellent article, Vince. Although I’m all-too familiar with the hands-on aspects of conventional ignition systems, having replaced or filed and set points continuously for some 50 years (my ’66 F100 still has the original system), I was never very good with the theoretical aspects. You’re an excellent teacher, and I am now ready to take the theory test, finally. 🙂
I well remember aftermarket transistor ignition kits being very popular in the late 60s and through the 70s. How good they were in some cases is another question. I seem to remember my brother and a friend, both of them were electronic buffs, making a system themselves. Probably not all that hard.
I have had a number of cars with conventional point systems, and rarely ever had any issues with them. These were all fairly low-revving engines, and not very fussy. Thanks to your tutelage, I can see why high performance engines had a greater benefit from these early electronic systems.
Many folks have urged me to replace the points in my F100 with a Pertronix or such, but it has never given me any trouble, and I have heard of these electronic units crapping out. No thanks! But then I don’t drive much.
Looking forward to the subsequent chapters.
Thanks for the feedback Paul! My wife works in education, so maybe some of her talent has rubbed off on me. I agree with your assessment on your truck. The points are fine. I have run Pertonix and they do seem to improve things a bit, but cost a lot more and can fail without warning.
I stick with the points in my old Scouts even though there are a number of options to ditch them. For quick starts on a warm engine nothing beats a carb and a set of points. The next time the points open it will make a spark. With a variable reluctance, or pulse inductance pickup you need some rpm to generate a strong enough signal to cause the module to trigger the coil. Throw in fuel modern sequential or direct injection and the engine may need to complete near two revolutions before it has enough information to be able to start making sparks and spraying fuel.
40 years of messing around with cars, motorcycles plus an engineering degree (BSME) and I really had it bass akwards. Thought the spark plugs fire when the points close! Looking forward to the next installment.
I have a (well) used dwell meter and timing light buried somewhere in the back of my tool cart. Haven’t used them for at least 40 years. Probably never will again.
My days of giving a substantial part of my paycheck to the Snap-On man are long gone. Their darn tools were so well made I couldn’t stand parting with them while they still had some value.
Someday soon the only people left who understand these old technologies will be specialists working on museum pieces. Wonder if any of them will want my tools.
Same here regarding the dwell meter and timing light. Somewhere in the shed, stuffed away in a box, buried under heaps of other stuff. Live long enough and your place becomes a museum of retro-technology!
Very informative, I have a car with points ignition it rarely gives any trouble however it is not my daily drive, The only electronic ignition systems I have had trouble with were on Australian cars Ford Holden(GM) and Chrysler,Reviving them when they fail varies with the make.
Great education for this elderly shade tree mechanic, who has done his share of tune-ups in the pre-transistor era, and has never really understood the newer stuff. Thank you and looking forward to the sequence.
(Still at it. Installed a new timing belt in my Metro this AM, and a new water pump and inlet pipe yesterday. Only had to swear once!)
Regarding the ballast resistor and 8V supply, I never heard of a ballast resistor system until the Chrysler Alpine was launched ( with transistor ignition) in 1975. I’m pretty sure the Lucas systems I grew up with were 12V only.
I had an aftermarket tansistor conversion on a BMC engine in the mid 70s, and it used add-on parts in the Lucas distributor. The only issue was that the distributor cap struggled to handle the higher spark voltage – which was also the case with the Alpine.
At one stage when my old mark 3 Cortina wasn’t running right, a mate who knew about cars (we all have them!) pronounced the coil was only getting 8 volts and wired in a direct 12 volt line from the battery controlled by an old brown bakelite 240V house switch mounted on the bottom of the dash – yeah, it DID look weird! ‘Use that when she’s not running right’ he said. It seemed to improve things, but positively ate plugs, points and distributor caps. Now I think I understand why!
The resistor wasn’t always a ballast resistor. Here in North America, Chrysler products typically used a ballast resistor, while GM and Fords used a resistor wire. The resistor wire performed the same function, it reduced the voltage/amperage. It was built in the wiring harnesses and wasn’t distinctive unless you knew what to look for. The one thing about the resistor wire was that it seemed far less failure prone than the ballast resistor.
Great article. A tricky topic well explained indeed.
Like Paul remembered above, electronic hobbyists were building their own transistor ignitions in the early days. Here’s a Popular Electronics from 1963 with a DIY project. I’m pretty sure I remember correctly that my dad tried one of these around then, but it failed pretty quickly.
Transistor ignitions were the first electronics to live under the hood right next to an engine, where the heat/cold cycles and vibration can be severe. Practically as demanding as military applications. Manufacturers of cars and of transistors found this out the hard way. It took these early applications to literally shake and bake them down to volume production longevity and cost requirements.
Aftermarket capacitive discharge ignitions, switched by breaker points, were briefly popular. They stored energy in a capacitor and that energy was sent through the coil when triggered by the breaker point circuitry. This resulted in much, MUCH higher voltage of longer duration in the coil primary and thus in the coil secondary and through the spark plug, resulting in s higher-voltage and longer duration spark. Problem was that the high voltage would cause arcing in some original coils, which of course were not built to withstand the higher voltage, and would fail.
I will discus CD ignitions in the next installment. They were briefly used by the OEM, including Porsche who used a Bosch system. They had their advantages, but ultimately there were better systems for cleaner emissions. They remained popular in the aftermarket for high performance use and are still commonly used today (MSD being the most common).
Much higher voltage from the CDI, yes, but also very short spark duration—opposite of what’s wanted. That’s on top of the issue you mention, of the higher system voltage causing problems by exceeding the dielectric strength of coils (and other components) not designed for it.
Thanks for all the great feedback and comments folks, it is much appreciated.
Excellent article on ignition 101.
A little real world comparison:
I have had my ’65 Chrysler for 16 years and had a ’74 Dart for 7. Call it 80 thousand miles on each.
The Chrysler had the standard factory points set up for about 5 years and then I installed an aftermarket (Pertronix) electronic replacement that fits inside the distributor.
The Dart had the factory transistor igniton with the box mounted on the fender.
I was adjusting the points about once a year, and replacing them about every other year.
The Pertronix unit cost about 9 sets of poonts, and a replacement factory box for the Dart cost about 4 sets of points.
I can’t directly compare between the two cars, but didn’t notice any real difference with the Pertronix swap other than saving half an hour’s work a year.
I’ve had no failures with the points or the Pertronix, and had to replace one box on the Dart. I think 2 ballast resistor failures on each car.
Great article, I find it amazing how many “mechanics” don’t know basic ignition theory. A local shop charged a friend a bunch of money to replace the points in a Datsun forklift that had quit. The new condenser didn’t fit under the cap so it was not installed. Then the coil was condemned. A few other people looked at this thing and nobody was able to make it run. I got it working by attaching the condenser to the negative terminal of the coil primary and jamming it under the coil mount to ground properly. It is running well a year later. My current daily driver Kadett 1100 still has points. They get were getting replaced yearly but I was lazy and just filed and reset them last year. Still running properly but for some reason it runs far better with way less dwell that specified. This seems counterintuitive to me as this engine spends most of its life at 3,000 RPM and above. I tried an electronic points replacer, but there was no performance, driveability or mileage improvement, actually a downgrade when the thermal grease melted out from under it and solidified on the breaker plate preventing the vacuum advance from working. I happily went back to points.
1. Don’t EVER file points. Delco recommends not replacing them until the deposits on one “point” is taller than the gap is wide. Keep in mind that the material deposited on one point has been torn off the other one. The wear-cone represents additional surface area for electrical conductance that is GONE when you file off the wear-cone.
1B. Quality points will be plated with Tungsten. Filing the tungsten off the points degrades them.
2. If your car runs better with “less” dwell, the engine is probably reacting to the change in ignition timing. Ignition timing changes one degree with every degree of dwell change. Check the timing. Reset the dwell to spec. See where the timing moved. Re-set the timing to what make the engine run best.
One of the more interesting trade-offs of the old points system is how they would wear-out gradually, as opposed to the electronic systems giving out without warning. When an engine began running badly, you just bought a complete tune-up kit, replaced all the components, set the timing, and you were back in business.
When an electronic system ‘did’ quit, how was it determined which part needed to be replaced? IIRC, it was one of those trial-and-error things where you had to buy one piece at a time, replace it, and see if it fixed the problem. This could get pricey as electrical components were non-returnable at auto parts stores.
All I can say about electronic ignitions is that they’re pointless.
Yes, but let’s not dwell on that fact.
It’s true – comedy is all about timing.
It’s useless to resist the puns in this subthread
I’m a little reluctant to ask in advance, because I don’t want to spark a detonation, but I just wanted to ping the participants here and ask if we can’t put a cap on it, can we at least condense the list a little?
Two thumbs up*, Vince; this article’s great and I can’t wait to read the next instalments!
Motorola published a fair amount of info on their electronic ignition system in their 1962 Annual Report (PDF, search for the word “ignition”).
* Way up! An epic tour de force—if you read only one article on CC this year, etc ;^)
Are you nominating this one for a CC Best of 2019 Award, Daniel? ;o)
Thank you kindly Daniel!
Fascinating! I always thought ChryCo was first to market with electronic ignition when actually they were only the first to adapt it on a mass scale.
By the way, voltage doesn’t flow. Voltage pushes the current.
This is a fascinating piece of work. I’ve been trying to find someone with in-depth knowledge of these breakerless Ignition systems to help me exactly replicate the ignition amplifier module used on the 1965-66 Ford GT40’s.
I need to identify the components used on these Modules that were effectively hand built by the Ford back room electronics guys. Ford’s archive Dept doesnt seem to have any circuit diagram for the PCB so I’m hoping you or someone here an help me work through it and solve the mystery.
All the Ford blueprint states is that this used “low cost breakerless transistorised ignition circuit.
I can get more photos of the guts of one of the modules showing the components of anyone here thinks they can help me!
…and here is a photo of the top of the module. There are what seem to be a pair of power transistors that are mounted onto the PCB
The whole Module was encased in incredibly hard epoxy which took two days to gradually pick out, but this damaged some of the components and stripped off any markings from the metal clad components.
The large capacitor however is a 40MFD and, we think, 50volt, and the brand of that is Mallory
Can anyone find the circuit diagram and component list for this module please?
The photos I want to upload dont seem to be attaching at the moment. Im just waiting to get the Registration process approved, then I can hopefully upload photos 🙁
Let me try again with the pic showing the top view of the same module, with the 2 power transistors visible.
Does anyone have any component info or a circuit diagrame on this exact Autolite/Ford system that was used just on the GT40s?