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50 Years of Ignition SystemsPosted 5/16/2001By Jim Linder
A 52-year-old technician and automotive instructor shares his views on the past 50 years.
Well, I guess that's my job. But at age 52, it will require little research. I have always had a love for cars and guess I always will. As an automotive trainer, I have not only worked on cars all my life, but also taught ignition systems since 1976, and have collected and worked on older cars for many years as well. “Bubba's Garage” is a real-life, old-time ignition repair shop located at 4-D and Gasoline Alley in Indianapolis. Bubba's Garage specializes in old vehicle ignition restoration and is the only place I know where a customer can still purchase a setup, reconditioned unit for a 1932 Ford V-8, as well as just about any old ignition needed! Bubba's may be seen online at http://www.lindertech.com; click on “Bubba's.” Oh well, enough about that. Let's talk about ignition systems and the changes we have seen for the past 50 years! Starting with the 1951 model year (50 years ago) is rather easy (but the word “starting” was much more difficult back then) as I still service many of these old units (Figure 1) and have applied our latest current ramping and scope technology to these old point-driven ignition systems. I remember when I got into this business, I thought that 10 degrees, 750 rpm and about 17 was all I needed to know about working on ignition systems. I still remember hearing those words thrown around the service station from time to time. You see, back then, all cars idled about 750 rpm, most were timed at 10 degrees before top dead center, and the adjustment for the distributor-mounted contact point was 17 thousands of an inch (or a worn-out dime, also very rare today). Just for you youngsters who may be reading this article, a picture of ignition points is shown in Figure 2. With a 6-volt system and a ballast resistor to protect the ignition points, we were lucky to get a strong 2 amps of primary current. In my mind it was a wonder the cars ever started at all! In many cases they didn't and relied on constant adjustments to start every time (hence the word “tuneup”). By 1961 (a 10-year jump) points were still in fashion but greatly improved with the advent of the 12-volt battery. A 12-volt system added some additional current for spark, but still required the much-needed yearly “tuneup.” Analysis equipment and tuneup scopes started appearing in the service bays and many shops started using these high-tech tools of the early '60s. (Figure 3 shows a 1958 Champion Plug Scope that still works today). These tools were fairly easy to master as you just looked at the screen and counted lines. A six-cylinder engine should display six lines. If you only saw five lines, then one was missing. Direction was then given to figure out which one (cylinder) was missing. 1971 brought many changes to the systems, one of which was a steady charging system that included an alternator. The racing community had adapted to a new point-free “transistor” controlled ignition system, and some early vehicles were being produced with a much-needed pointless system. Although these units were only used on special applications, they did prove the point (no pun intended). These systems raised the applied current to the primary and appeared somewhat reliable and trouble-free (at least for the limited production numbers). This Pontiac unit (Figure 4) required that ALL ignition wires be replaced as a set! 1981 brought just about every OEM using at least one vehicle line with the new-style electronic ignition systems, but a new era of “electronic spark control” was born as well. Many farmers bought up the Oldsmobile MISAR-equipped vehicles only to find out they didn't work well in the fields. These vehicles had a crank sensor and trigger wheel mounted on the harmonic balancer and it didn't hold up well when wheat and straw wrapped around the harmonic balancer. Wow, not only had the old points gone by the wayside, but the centrifical advance weights had been replaced by a new system that could now do the job with no moving parts (to stick and wear out - the actual problem all the time). I still have memories of attending a factory GM class - that's back when they had them for all of us - and the instructor showed us the early 1981 CCC computer systems (used in California since 1979). He claimed the system could actually change the spark and fuel 10 times per second! We discussed that on the way home, thinking that was the fastest thing we had ever heard of on a vehicle. Wow ... pretty slow compared to the 41,000 data bytes per second some are claiming today! Any technician out there that experienced those early '80s vehicles remembers the service problems caused by these early systems with adjustments, electronic parts failures and often stuck-on, dreaded “MIL” lamps - a fun part of my learning career, for sure. In my opinion, the '80s also brought on the downfall of many OEMs and - for a brief while - I honestly believe no one made a good vehicle. (That could be a discussion for a later article for sure). The 1991 model year brought the advent of the first reliable electronic-equipped ignition systems with most defects being weeded out from the 1984-1987 years. The new boy in ignition land was a newcomer to the world called DIS (or distributorless ignition system). Not only were the old distributor points and condenser gone, but the distributor itself had flown the coop as well. A new crank trigger told the system when to fire and now we actually fired two cylinders at the same time, one on exhaust and the other on compression! (I still contend DIS was an accident created by the engineers wondering what to do with the energy created by the technician who had left the ground wire out of an early HEI system; see Figure 5). With the 1991 model year, we started to see almost every OEM produce a much more driveable vehicle with less overall “tuneup” service needed. Many owners took this to heart and just quit doing “tuneups” at all! The '91 models not only had high energy (higher primary amps), but used electronic spark controls. At this time, very few models were without the latest “fuel injection” systems replacing our old friend (or old enemy), the carburetor. During one of my latest hiring interviews, Michele “The Analysis Sleuth” Winn stated she did not service carburetors or distributor-equipped vehicles. Wow! Not only had I hired a female technician, but one with a “no carburetor or distributor clause&3148; in her contract! This, by the way, was a very good decision for both of us! 2001 brings many new systems into play in the automotive service world with the old DIS systems now being called “EI” (due to the latest OBD-II terminology) and the old systems with distributors now being called “DI” for distributor equipped. Just when I finally had the terms straight in my old mind ... With the advent of the latest OBD-II and emission testing sprouting up across the country, many OEMs have created newer systems including coil on plug (COP), direct ignition system (with no plug wires) and cassette ignition (single module with multiple coils). The overview on ignition changes from the last 50 years is really very simple: They all have increased primary current to the coil, a much improved (faster) rise time to ramp and fire the plug gap, and offer a much more reliable ignition system than ever before. I think I may give up distributors myself ... nah ... that would make me a punk, right?
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You know you have been in the industry a long time when you can do a 50-year report on the changes in ignition systems from the cuff with no research.
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