When you are working with a vehicle that makes around 65 horsepower to the rear wheels, you need that power to work as efficiently as possible – loosing up hill drag races to semi trucks can be embarrassing. Adding insult to injury is a vehicle that can’t even get good gas mileage on that little horsepower. If you have ever owned a classic car with a stock inline 6 cylinder, you know exactly what I am talking about. Though with DUI’s (Davis Unified Ignition) HEI Performance distributor, we were going to gain back some of those lost ponies… and fuel economy.
Our Project “Biting the Bullitt” 1965 Mustang still retains its early-model 170ci inline 6 cylinder. These engines made right at 105 horsepower from the factory in prime condition, and we know that in its ‘less than prime’ state, we are lucky if it’s making 65 of those ponies to the rear wheels. We are going to be yanking the dying engine for a 1000HP 427ci in a few months, but I wanted to get all I could out of the engine before it is yanked.
When I bought the Mustang, it had been sitting in the previous owner’s garage for some time. Even though it ran, it ran rough. Running wide open from stop light to stop light just to keep up with traffic wasn’t making things any better. I started with all the simple updates – new air filter, PCV, spark plugs, and a oil change. None of that helped. Next up I installed a rebuilt Autolite 1100 carburetor. While this helped regain some of the drivability, it didn’t help the performance factor at all.
The Load-O-Matic was one of the first types of vacuum advance distributors
Ditching the Load-O-Matic distributor, or should I say a Load-of-….
A Load-O-Matic distributor is an old bit of technology and provided one of the first versions of a vacuum advance distributor. While this was the hot ticket when it was new, it has since been deemed archaic and troublesome. The design is far from the “just hook it to your intake manifold somewhere” and uses a dedicated port for the vacuum reference that uses a blend of manifold and venturi vacuum to advance through the points-type distributor. All of this action is controlled through an integrated Spark Control Valve (looks like an externally mounted power valve) to relegate the blend of vacuum sources. That means if you need to replace the vehicle’s carburetor, one that has an integrated Spark Control Valve will be needed for the engine to operate properly. Worst part of all, these distributors had no previsions for mechanical advance.
A popular upgrade for the Load-O-Matics is to upgrade it to a electronic type ignition module to get rid of the points parts. This is all well and good, but there is nothing that you can do to fix the vacuum advance portion of the distributor, which is also very prone to cracking and vacuum leaks.
A Simple Answer to your Prayers – The DUI Plug and Play Distributor
DUI has a wide variety of plug and play HEI-type distributors as well as Ford Duraspark offerings as well. We went with the HEI-type due to its simplicity – there are literally two wires here. Also, DUI goes a bit further than most companies by custom calibrating the distributor to your driving style. That means if you have a stock vehicle running on 87 octane or a highly modified car running on premium, Performance Distributors will hook you up accordingly. But even the best part lies in the advance which offers a traditional vacuum style advance that will hook up directly to a intake manifold vacuum source. Also we chose a set of pre-assembled and labeled LiveWires to help deliver that additional spark energy.
DUI Street/Strip Distributor 39820-144
• Custom calibrated timing curve for 87 octane operation
• Two wire connection (power and tach) with integrated coil
• 50,000 volts of spark energy
• Traditional vacuum advance that hooks to an intake manifold vacuum source
• Billet base construction
• Pre-fitted and labeled per cylinder
• High temperature sleeves
• Spiral wound core prevents electronic interference
• Comes in red, black, blue, purple, yellow, and silver
Installing the DUI distributor and LiveWires
First disconnect the wires running from the stock distributor to coil and the vacuum advance line. Remove the cap and note the direction in which the rotor is pointing. We recommend hand cranking the balancer over until the distributor lines up with the number one spark plug wire so there is no confusion how how the distributor lines up.
There is just the one bolt that holds the distributor in place by the hold down clamp. The distributor uses a keyed oil pump drive that might get stuck and not want to come out easy. I found that lightly and quickly rotating the crank pulley back and fourth while pulling up on the distributor from the mid-shaft area made it easier for the distributor to come out.
There are three fastening tabs and one connector that must be pulled to get the DUI distributor cap completely off. Line the rotor up in the same spot, making sure the distributor keys up with the oil pump. A little persuasion was needed to get the distributor back in place, using the same method on the crank pulley jiggling allowed for an easier install.
The biggest part of the actual install might be a little bit of wiring. The DUI distributor requires a full 12 volt power wire and most stock vehicles will more than likely be on the ballast resisted 7-8 volt source. An easy way to check is to turn the key to the on position (not start) and use a simple volt meter at the coil. If the wire is resisted, you can wire a bypass hot 12 volt wire from the key switch to the distributor, remove the resistor, or wire a simple relay.
For the sake of time and simplicity, we went with the relay. We wired the existing resisted power wire to the relay’s switched power source, a power and ground to the battery and then the new 12 volt wire directly to the BAT terminal on the distributor. Then if you have a TACH, there is a terminal right next to the BAT hook up, and that’s it!
The LiveWires come with a tube of dielectric grease to keep the boots from sticking to the spark plugs. We applied a little inside the boot and also on the spark plug's porcelain. Just incase you forgot, the firing order is 1-5-3-6-2-4
With the vacuum advance not connected, we fired up the car on the first try. When it comes to timing the car, we went with the vacuum method. The stock Mustang balancer is notorious for having problems with the balancer slipping and not showing true time. After setting the idle air mixture again, we rotated the distributor until the maximum amount of vacuum was present at idle. We then utilized the vacuum port on the back side of the intake manifold for our reference. As a double check, we drove it and checked the plugs to make sure there wasn’t any detonation.
We were impressed with the performance we gained from the DUI distributor. There was a noticeable difference in reliability and the power gain. Also, we picked up about 4 MPG over our old Load-O-Matic. For about two hours worth of work, the upgrade was totally worth it. Now we can get some lasting mileage out of our small six, that is, until we yank it for our 1000 HP 427ci monster.