As Tested By Benjamin GeersWiring; some guys take to it, while others would rather scrape undercoat than pull out a set of crimpers. When it comes to ignition systems and reliability, there isn't a case to be made against any of the proven electronic ignition systems. Some systems are as involved as a science project to install, which is fine if routing those electrons is your thing. Davis Unified Ignitions took the opposite angle, making the installation of an electronic ignition a simple one-wire hookup-and the wire is already there.
The Davis system is based upon the GM HEI, which may cause a purist to cringe. However, there's no denying that continual development and refinement by aftermarket firms such as Performance Distributors turned GM's knuckle-dragging factory setup into a respected high-performance system.
The self-contained system, the DUI, is available in two basic configurations for small-block Mopars: a street/strip unit rated to 7,000 rpm, and a race version capable of 9,000. The DUI is built on a billet housing carrying the distributor shaft on two bushings. The advance mechanism is top-mounted for quick and easy distributor curve tuning, although Performance Distributors custom tailors the advance curve for the intended application. Options such as locked-out vacuum advance are available for specialized applications. With the electronic HEI module mounted inside, and the coil in the cap, the Davis distributor needs no external extras to work. Just a hot 12V wire in, and it's ready to run. A second terminal is provided for a tach hookup, which, like the power feed, connects with a common spade terminal.
Since the cap is a large GM HEI type, the DUI has serious girth. Combined with the tall housing, the DUI distributor dwarfs the stock-style distributors. With its larger-than-stock size, clearance can be a problem, and it just won't fit in an A-Body. To meet those applications, Performance Distributors offers the "Tri-Power" ignition. Basically, the Tri-Power is an adaptation of the stock Chrysler electronic distributor, wherein the OE-type magnetic pickup and reluctor sends the triggering signal to a module mounted externally on the housing. The "piggybacked" module is prewired to the distributor. This eliminates the need for a remote ignition box, although an external coil is retained. Performance Distributors provides a matched high-output coil with the system, which can mount in the stock coil location. As with the DUI, no ballast is used with the "Tri-Power" system. To install it, the factory ballast is bypassed, and a full 12V is supplied to the coil and module.
We had all three to try, and the systems all performed. A "Tri Power" system along with Performance Distributors' LiveWires secondary leads were installed for evaluation on one of our street A-Bodies over a year ago, and has required no attention or maintenance since. We had an opportunity to try the DUI system on a street/strip 360, and found the distributor handled the spark requirements of our 475hp engine up to our self-imposed redline of 7,000 rpm without trouble. The ignition timing was very stable.
Recently, we tried a Performance Distributors system in an old Dodge truck, still sporting a single-point distributor atop it's swapped early small-block. The nice thing was that clearance problems would be addressed. While this isn't a drag machine, we figured increased reliability and lower maintenance would be reason enough for the change. The changeover was amazingly simple; just a matter of bypassing the stock ballast resistor, removing the stock distributor and coil, and running the old coil's "+" wire straight to the DUI. A set of LiveWires completed the upgrade.
