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1975 Dodge Truck - Davis Unified Ignition Distributor Install

Posted in How To: Engine on May 1, 2007
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How can you say "no" to simplicity, reliability, and an increase in power? Yeah, neither could we. Our old '75 Dodge workhorse with a 440ci engine (the Lawg) was still running the factory ignition junk from the '70s. And if there was one thing that might leave us cold on the side of the road in this old Dodge, it was the sketchy stock ignition. The ignition systems were subpar when they were new in the '70s, and 30 years later we were just asking for it by not upgrading.

Performance Distributors has been in the business of improving ignitions since this truck was new, and its D.U.I. (Davis Unified Ignition) H.E.I. distributor upgrades are available for most older small-block and big-block Chevy, Ford, and Dodge engines. The all-in-one units based on the GM H.E.I. allow you to delete all the ballast resistors, modules, ignition coils, and a ton of wires from under your hood, replacing it with an all-encompassing unit that only needs a single-switched ignition wire to run. How much easier can you get?

We recruited the help of our local Southern California Chrysler specialist, Damian Smith, to help us out with the install.

Damian Smith pulled out our factory ignition junk in just a few minutes. The coil can be thrown, and the distributor comes out with the removal of a simple bracket that clamps it into the engine. But we found it best to leave all the ballasts, resistors, modules, and whatnot under the hood until we were sure we had the truck running. If you have fitment problems or can't get your D.U.I. distributor to work, you might need to get that old ignition working again, so Damian warned us not to get too snip-happy with the wire cutters just yet. The D.U.I. ignition requires one switched-ignition 12-gauge wire lead to run. This might prove harder to find than it sounds. You need to find a switched-ignition hot lead that will stay live not only in "On" position, but also in the "cranking" key position, so you will have juice to your distributor while turning over the engine as well. The single 12-gauge wire runs into one of two connections on the D.U.I. distributor (the other is for a tachometer) and (theoretically) is all it should take besides a set of spark-plug wires.

The D.U.I unit has quite a bit bigger cap than most distributors. Therefore, to get it into a Dodge big-block that has an angled distributor design, it has been made with a much longer shaft to clear the accessory drives on the engine. Look at how much longer it is compared to the factory junk (in hand). Depending on how hodge-podge your truck has gotten over the years, you might have to adjust a couple of things to get everything to fit right. We had some funky non-original alternator and belt combo that was getting in the way, but it was nothing Damian couldn't fix with some bigger belts and a little more spacing on the alternator brackets. You can get your color choice of caps as well, but we went with the clear cap, where we could actually look through and see that we were getting spark as the rotor turned.

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Performance Distributors
Memphis, TN 38132

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