Are They Really Worth it?
Electronic ignition point replacements have been around for a long time. They have always been marketed as better than stock, but is this true? In this article, I will look at the advantages and disadvantages of using these systems. As well as my opinion and what I use in my own cars.
To understand the electronic ignition points, we first need to understand what the points do. Ignition points or breaker points are part of the Kettering style ignition. They are a mechanical spring-loaded switch. The switch is housed in the ignition distributor. Ignition points are the trigger for the spark event. In a Porsche application, they are used in two different ways.
The 356 and 912 models use a conventional ignition system where the points are directly controlling spark energy. When points are used to control the amount of spark energy they are put under a large electrical load. This load is due to the ignition coil charging effect. This will cause the points to wear quickly requiring frequent service.
The 911 models use a CDI ignition system. The CDI box is what generates the power for the ignition system. The ignition points in this system are used as a trigger point only and are placed under a very light electrical load. This means that ignition points will last much longer. Though they will still require service, just not as often.
Electronic Ignition Points
Electronic ignition as the name says are simply an electronic version of the mechanical ignition points. There are two main types of point replacements available. They are offered in optical designs or a Hall effect type. Though they work differently both systems will do the same job.
An optical point replacement system uses a photoelectric diode and a shutter wheel. The shutter wheel is installed on the distributor shaft and the diode mounted on the breaker plate. As the distributor turns the diode senses the openings in the shutter wheel. This causes the transistor to switch from ground to open, which triggers the firing event.
The hall effect system uses magnets that are installed onto the ignition distributor shaft. As the shaft rotates past the pickup transistor they cause the system to switch from ground to open. Thus, causing the ignition system to fire.
Advantages of using electronic points
Electronic point systems will reduce the amount of service that the ignition system requires. Though the system will still need other routine maintenance. Using electronic point systems will replace both the points and condenser in the distributor. This means fewer parts to routinely replace. Electronic points will be more accurate in the firing point and are less affected by engine speed. This is because the electronic points do not have any wearing components or springs. On a mechanical set of points, the rubbing block and point contacts will wear. This wear changes the firing point, which will affect ignition timing and system performance. mechanical points also rely on a spring to close the contact. This spring often cannot keep up with higher revving engines, resulting in point bounce.
Some electronic point systems will claim that they have easier starting or higher performance. This can be somewhat true when using a standard, (non-CDI), ignition system. Systems like the Pertronix Ignitor II will vary the dwell times to change coil saturation time. Increased coil saturation equals higher spark energy.
Disadvantages of using electronic points
Electronic points are expensive when compared to standard points. Often an electronic point system will cost between $80.00 to $175.00 or more. A standard set of points will cost between $5.00 and $20.00. Electronic points can and do still fail. This means having to spend the high cost again.
Electronic points will require extra wiring to install. Usually, this means running an extra ignition power wire to the coil or other power source. For concourse cars, this can be an issue having extra nonstock wires.
Some electronic points can be affected by other standard ignition components and can cause them to malfunction. The Pertronix Igniter II systems use a small microprocessor to control the dwell time. This is not compatible with solid core ignition wires. All Porsche models use solid core ignition wires so using those types of systems are out.
The hall effect system can be affected by temperature. Both the magnets and the electronics used in the trigger system will change with temperature. When using this type of system in an air-cooled application can result in issues. It is normal for an air-cooled engine to operate at 250°F or higher. This seems to have an ill effect on the signal quality of the Hall effect sensors.
My opinion on electronic points is that they are not worth the expense, and at least, as it regards to Porsche applications and here is why.
First, the initial outlay for the system is high compared to the cost of buying replacement points. In some cases, I could buy ten sets of standard points to one electronic set.
Secondly, there is no performance gain. Because all Porsche models use solid core ignition wires the use of dwell changing systems are out. Also, in the 911 models that use a CDI box, the CDI is responsible for ignition energy, not dwell time. In fact, if the Pertronix Ignitor II system is installed in a car with a CDI box it can result in other ignition system component damage.
In some cases, I can see a benefit. For example, if the points cam has worn out in the ignition distributor. Because normally this would result in replacing the entire distributor. However, because the electronic point systems don’t rely on this part you can save a distributor by using an electronic point system.
The other benefit would be if the original ignition points are no longer available. Even if the aftermarket electronic point manufacturers don’t specifically make a replacement set for your car, typically one can be modified to fit.
My personal Choices
My advice would be it’s a personal choice. In my own cars, I choose to use the original points. If you decide to install a set of electronic points choose carefully. My preference, when I must install an electronic point set is normally to use an optical set. however, in recent years those types of systems are getting harder to find. Make sure to carefully read the instructions before purchasing and when installing an electronic point system. Make sure that they are compatible with your application. Lastly, don’t expect any change in the vehicle’s performance. Especially if you are just changing to an electronic because you want to. Remember in most Porsche application points have no bearing on spark energy.
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1 thought on “Using aftermarket electronic ignition points”
Excellent article! I understand most all of what is said but I am a bit unsure on what dwell time means? Will you be publishing some articles on dwell time?
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