Often, manufacturers’ eyes are focused forward, looking to the next latest and greatest application for their products. While Performance Distributors does aim to be up to speed with the latest and greatest, they also realize that there are plenty of ignored markets that still enjoy popularity within their respective niches.
To that end, we decided to take a look at three of the company’s vintage specialty applications, where they identified the need for improvement, developed a modern ignition system that incorporates with the old-school architecture, and brought a new performance option to an otherwise underserved market.
The System Core
At the core of all of Performance Distributors’ vintage applications is the Davis Unified Ignition – or D.U.I.
“The Davis Unified Ignition is Performance Distributors’ version of the GM High Energy Ignition (HEI) distributor,” says Steve Davis, President of Performance Distributors. “The DUI is a one-piece, one-wire ignition system. The DUI Coil is mounted inside the distributor cap and the Dyna-Module is in the distributor.”
The compact, simple design lends itself well to a wide number of applications, because it fits just about anywhere a standard distributor fits and has all of its electronics – the distributor, coil, and control module – integrated into a single unit, requiring no additional wiring or components, while upgrading each of those components to modern, performance-oriented pieces.
The brain of the D.U.I. is the control module called the Dyna-Module and is integrated into the distributor itself.
“The Dyna-Module has two to three degrees of additional dwell time calibrated into it, compared to stock modules, throughout the RPM range,” Davis says. “The extra dwell time allows whatever coil you run to saturate longer, intensifying the spark that winds up at your spark plugs.”
The brawn of the D.U.I. system comes from the upgraded Performance Distributors coil integrated into the distributor cap. “The D.U.I. coil is tricked out with more windings and larger diameter wire internally. This allows it to fire well into high-RPM, while the stock coils are bad about dropping off in the mid-range,” Davis says.
“The DUI coil maintains 50,000 volts under load, and that robust spark allows you to run wider plug gaps –.050 to.055-inch. That, combined with the additional duration from the Dyna-Module, may allow you to run less timing due to increased spark efficiency.”
As an assembly, the D.U.I. system comes from the factory preset with a smooth timing curve, designed to give you instant throttle response from idle to your rev-limit, without any stumbles. “Every unit is calibrated on a distributor machine with a coordinated mechanical and vacuum advance,” Davis says. “That part is critical to maintaining throttle response and preventing any bogging or detonation.”
The modern D.U.I. electronics make for an impressive ignition upgrade in any application, but really shine when replacing an old, worn, and outdated OEM ignition, as in the three applications we discussed with Davis.
The Buick Nailhead
The Buick Nailhead was the first production Buick V8 engine. It was produced between 1953 through 1964 with displacements ranging from 264 cubic-inches to 425 cubic-inches. The Nailhead version of the Performance Distributors D.U.I. came about strictly due to a customer request.
“A guy came by our booth at the SEMA Show a few years ago who had a 401. He asked if we offer a distributor. At the time we didn’t, but told him if he would send us his stock distributor, we’d try to build him one,” says Davis. “He sent it and we built it. After a couple of months of him running it, we called it a success and added it to our product line.”
By replacing the stock breaker points style ignition, the D.U.I. system creates a voltage that is unheard of from a points-style ignition.
“With a points-style ignition you can only run a .025-inch plug gap,” Davis says. “You can run a .050-inch plug gap with a D.U.I., which translates to a lot more spark energy at the plug.”
To complement all the additional ignition power, Performance Distributors offers replacement wires from their “Live Wire” lineup.
“Stock replacement wires for the Nailhead have way too much resistance for the voltage which the DUI produces, so they are a needed upgrade,” says Davis.
The Ford Flathead
The Ford Flathead V8 is the original Blue Oval hot rod engine. Produced from 1932-1953 in the U.S., this iconic engine is the oldest of the three vintage applications we’re talking about in this article. It still enjoys a healthy aftermarket presence, so it’s not really a surprise that the application is covered by Performance Distributors.
“We got a lot of phone calls and emails from customers wanting to upgrade their Ford Flathead ignition systems,” Davis says. “That made this application a no-brainer.”
The Ford Flathead was a points-style ignition from the factory, with shortcomings similar to those of the Nailhead.
“Another problem with a points distributor is that you have to run a resistor to prevent the points from burning up,” Davis explains. “The resistor reduces the input voltage to the coil down to 10 volts or less, whereas the D.U.I. likes the full 14.5 volts from the alternator.” It only makes sense that the more voltage that goes in, the more voltage that can be put out.
Again, like the Nailhead, the stock plug wires are another bottleneck in the ignition system, with the low-resistance, 300-350 ohm-per-foot Live Wires being worth six to eight more horsepower on the Flathead, with the D.U.I. installed.
Volkswagen Type 1 Air-Cooled
The third application is a bit of an oddball, as it isn’t a domestic engine or a V8. Actually, the VW Type 1 Air-Cooled engine is about as different from the other two on this list as you can get. The flat-four air-cooled engine was first produced in 1936 and existed in various forms up until the end of the 20th century – so to say they were prolific would be an understatement. In addition to its sheer production numbers, it has an almost-unmatched versatility. The air-cooled engine can be found powering everything from drag cars to sand rails, and there are even versions of the air-cooled VW engines powering aircraft.
“We had developed DUI Distributors for some off-road applications like Jeeps and Land Cruisers,” says Davis. “I saw quite a few guys were running the four-cylinder VW engines too, so it seemed like a solid market to get into.”
Like the other two engines, the Type 1 engine was originally equipped with a points-style ignition, and lent itself beautifully to the D.U.I. upgrade. However, there is more to be considered with the Type 1 application, as the engine enjoys a very healthy aftermarket, with full-race builds and forced-induction commonplace.
“We actually have two versions of the VW Type 1 D.U.I. system,” says Davis. “The Street/Strip version will fire to 7,000 rpm, while the Race ignition will function all the way up to 10,000 rpm. Generally speaking, the Race version will also have a much quicker advance curve.”
Slapping a turbocharger on an air-cooled VW engine is a time-honored modification, especially when the engine is being used in something other than the original Beetle chassis. When dealing with the increased cylinder pressures offered by boost, spark energy becomes even more critical.
“Not only does the increased spark output work well in the boosted applications, our machine-calibrated advance curving really plays a large part in avoiding detonation,” Davis says. “We are able to dial in just the right amount of advance for the boost curve.”
One final difference between the Type 1 and the others on the list, is that there are some factory and aftermarket EFI conversions for the engines. “If the computer doesn’t control the timing advance for the system, the D.U.I. system will work with a fuel-injected application,” Davis says.
Modern technology has improved the performance of engines exponentially over the decades. Not only is it awesome to see a company applying that modern technology to legacy platforms and increasing their performance, reliability, and drivability, but doing so in a visually-unobtrusive and simple-to-install package such as the Performance Distributors Davis Unified Ignition system.