Each system has a unique advantages over the other two. As such, it may be more desirable to install one system, as opposed to the other two, to better suit your needs. For example, the Pertronix is perfectly suited to a concours restoration, as it is completely hidden under the stock distributor cap, however it offers the lowest gains in performance. A nice feature about the Duraspark is that it can be installed on a tight budget, then up-graded when your budget allows. However it's the most difficult to install. Depending on the ignition box you choose, the wiring can be complex and confusing for some. On the other hand, the Pertronix and DUI are very easy to install. The DUI offers superior performance and the highest horse power gains, but it's also the most expensive system of the three, at least in terms of up-front cost. Which we'll explain later.

PERTRONIX: If you need to maintain the stock ignition system, say for a concours restoration, then a Pertronix ignition module is the only way to go. The Pertronix module is installed where the points use to be, so it is easy install and completely hidden under the stock distributor cap, there-by maintaining a stock appearance. Pertronix also offers 7mm spark plug wires to improve performance, yet they too maintain a completely stock looking appearance. The Pertronix Ignition modules are a great product for those working on a contours restoration, however we believe they have two major drawbacks. First and foremost, most conventional distributors, like the Duraspark and DUI, use mechanical advance (centrifugal weights in the distributor) to compensate for changes in rpm, which immediately swing out when rpm's are increased. Whereas the stock "Load-O-Matic" distributors (60-67) use venturi vacuum and a vacuum canister, which reacts slowly to the relatively weak venturi vacuum signal. As such, the "Load-O-Matic" distributors are very slow to provide spark advance when the engine is accelerated under load, and they are notorious for soggy acceleration. The stock and/or rebuilt Load-O-Matic distributors also use a single upper busing to support the distributor shaft, and like everything else, they wear out over time. When the bushing wears out the rotor begins to wobble, causing spark scatter and fluctuations in ignition timing. Therefore, while the Pertronix module increases spark quality, your still stuck with the poor operation of the "Load-O-Matic" distributor. Another thing to consider, six-cylinder Pertronix Ignition modules are usually a special order item, since most parts stores only carry Pertronix modules for V8 applications. Therefore we suggest keeping a backup module, or extra set of points, in your toolbox or glove compartment in the event of an unexpected failure. For more information, please read our tech articles on the Pertronix Ignitor, and the Load-O-Matic Distributor, which explains both items in greater detail.

DURASPARK: If a contours appearance isn't an issue, yet you want a dizzy that looks somewhat stock, the Duraspark II might be your best choice. Not only is the Duraspark II an excellent ignition source for those on a tight budget, it can be upgraded at any time. Most inline enthusiast prefer to run the DSII with either the Dyna Module (available from Classic Inlines), the MSD-6A (without rev limiter) or the MSD-6AL (with rev limiter). If your on a really tight budget, you can even build your own, using any 4 pin ignition module and a good heat sink. The biggest drawback to the Duraspark, is wiring and installation. Make sure you have the proper wiring diagram which is intended for your application, and that you know where every wire goes before you start. Check and double check the wiring, making sure it's right before you re-connect the battery cables. Failure to do so may cause an electrical fire, and/or damage to your electrical and/or ignition system. If your not sure, ask for help......

wiring diagram for the DSII with the stock Blue Strain ignition module

DUI: Like the Pertronix, the DUI is very easy to install, as it only requires one wire to a hot 12V supply. The most common way of doing this, is by running the hot wire from the distributor to the ignition switch. Or you can use a relay, which is the preferred method. Using the relay makes the wiring a little easier since you don't need to climb up under the dash or pull the instrument panel to get to the ignition switch.

stock wiring diagram

Never wire the DUI directly to the old hot wire without using a relay. The reason for this is simple. The old wire normally has a resistor somewhere in the line, which is usually behind the instrument panel. The resistor reduces voltage to the distributor, which in turn reduces performance. For the best results, you want a full 12 volts going to the distributor.

DUI without relay (by-pass required)

DUI with relay (by-pass is optional)