Project Shovelle – Electrical System Prep 101

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By Tim Baillie (HzEmall Customs)

Normally, when people build a car, they figure out their drivetrain and dump a big chunk of change into that. Then they get their bodywork done, the car painted and they forget about the wiring till last and usually don’t have any money left over or not enough. So they buy a used “better shape” harness or just put back in the original harness into the car, or buy that $149 eBay special (which is just junk).

The first and most important part of doing a rebuild on a car is making sure that you have a solid electrical system in place for everything to run on. If it’s a full restoration, full race car or something in between, if the car is not wired properly, is not grounded properly and isn’t using all the proper wiring and connectors, nothing in the car is going to run properly……ever.

One of our specialties here at HzEmall Customs is electrical systems. Our guys here have over 60 years combined experience when it comes to vehicles’ electrical systems. We are also some of those few strange people that really enjoy wiring (yes they do exist out there, don’t laugh) so we like what we do and we spend the right amount of time doing it.

Project Shovelle was in really good shape when we got it and while the electrical system was, for the most part, unmolested, it is still over 40 years old and the wire and insulation is brittle and has some corrosion in the copper stranding (they all do). With the new components, as well as more modern drivetrain, we wanted to make sure we had a strong electrical base to work with, and that is why we dedicated a realistic amount of our budget towards the electricals.

We started by doing some research and getting a factory wiring diagram for the ‘68 Chevelle. We went through it and figured out what options and circuits the car had in it. We figured out which ones we were going to use and which ones we weren’t going to use. Each component works a certain way in each car so we wanted to make sure that we had the information on how things like the heater, wipers, etc were wired so they were hooked up the same way and still worked. For example, a wiper motor in one year of car isn’t always wired the same or even work the same the following year, so knowing your car’s components is important. We then sat down and made a list of all the additional items that we were going to add to the car and started to design the electrical circuits for each item and how we are going to incorporate them into our Painless Performance 18 circuit ‘68-’72 GM Muscle Car harness system. Because this is a universal harness, we added our own circuits where we needed to and changed a few things to suit our build needs.

We changed things like using the coil fuse (ignition controlled) for the ignition needed for our ECM harness. The power window and lock fuses will be used for our alarm system and fuses like power antenna and cruise control will be used for other things. This is nice because you’re not tapping into other circuits for fuse protection, you’re allowing each item to have its own fuse.

We started by removing the old harness carefully from the car and labeled every wire and wiring molex connector as we went along. Once we had the harness removed, we could lay the harness out on the table and one-by-one go through and take pictures of the stock molex connectors and draw out our own diagram as to what wire went in what hole. We then got our 1968 electrical wiring diagram (www.autozone.com is great source for this older stuff) and started to get to work.

We took our Painless harness system and laid that out to compare what was the same and what was different. The OEM bulkhead connector for the firewall is the same (which is a bonus right off the bat) and most of the colours are still all the same (Painless uses GM wiring colours on almost all of their harnesses). We then started one circuit at a time, removing the molex plugs off the stock harness. We cleaned them up and decided if they were to be reused or if they needed to be replaced. Now, some OEM molex housings are available through different aftermarket companies, but sometimes you have to re-use the original plastic housing to be able to fit onto its original component because this wasn’t a generic molex or something.

Next, we took all-new copper terminals and soldered them onto the Painless wires and plugged them into the new or original molex housings. Building each harness at a time allows for a neater and easier way to install the harness. Then we wrapped each individual harness in Painless Performance’s new slit braided wiring wrapping to protect each harness and to clean up the underside of the dash once it’s installed in the car. Using a home electrician label kit, we can label each harness as to what it is so that six months or six years from now, you know what you’re dealing with.

Part of doing a proper job is making sure that we use proper relay systems for certain circuits that require a little more voltage than others. By using a relay, you allow the circuit to receive full voltage no matter how long your wiring run is. In Project Shovelle, we are using a separate fuel pump relay harness, brake switch relay harness and an H4 headlight relay harness system. This one not only makes sure that your headlights get full power from the battery, it also allows the low beam to stay on while the high beams turn on, giving you greater output to see at night.

Each car we wire up gets its own file for diagrams, manuals and pictures for the entire electrical system. We make sure that in the future, we will know exactly how we wired the car and where and what each component is.

This process takes a little more time and might cost a little more than your average “I got a wiring guy” but in the long run, it’s done right the first time and will never be a weak link in your car.

Just remember, the most important thing in your car is proper ground….

If you have any questions about electrical systems give us a call at HzEmall Customs (604) 888-6568 or info@hzemall.com