Project Blank Slate - WiringShorts, splices, and sparks–the three “Ss” that every person dreads when working on an electrical system. The electrical system on a car is similar to the human body’s nervous system–it’s what makes everything happen, from movement of the starter to the flashing of your brake lights. The electrical system is by far the most important system when it comes to getting your project from rolling body to full-on operational. Without it there’s no spark for the combustion cycle, no fuel pump to feed the motor, and no headlights to see at night.

Being one of the most crucial elements in a car’s operation means that your car’s electrical system should be in top notch shape. To the dismay of those taking on pre-owned projects, this is one area that most people deem themselves professionals in. While the tedious and detail-oriented DIY enthusiasts are certainly out there, we have seen time and time again hacked and half-hearted wiring efforts in order to add extra accessories or remove unwanted items. Combine that with years of driving and you can end up having is one massive nest of wires under the car just waiting to short out and leave you stranded–if you’re really unlucky, leave your ride up in flames.

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A lot of loose wires in the cockpit can be frustrating. A good wiring harness eliminates a lot of the frustration of wiring a project car.

Starting From Scratch

Project Blank Slate, our 1969 Camaro, had a huge mess of wires under the dash. It was cut, spliced, taped and didn’t even work properly. We decided it wasn’t even salvageable, so we ripped the whole thing out. With absolutely zero wiring in the car, we laid out a plan to wire this car up and have everything working better than new. But we had a few obstacles to overcome; for starters, we knew that we wanted the battery located in the trunk for weight distribution and to clean up the engine bay. Secondly, we knew that with our LME 502 cubic-inch LS engine, we wanted to use an OE-style engine harness.

Our wiring harnesses are carefully reproduced using the original General Motors schematics, and feature all the correct attachment connectors. -Ray Yaeger, Classic Industries

We decided to give Classic Industries a call to seek their knowledge about wiring options and to see what they had available. From there we gave Ron Francis Wiring a call to get more information on a trunk-mounted battery cable kit. Lastly, we needed a battery box so we contacted Moroso. We wanted to find out a little bit more about each item:

Catching up with Ray Yeager of Classic Industries, he gave us some more information on the wiring harnesses. “We offer a stout range of replacement wiring harnesses. One thing that’s nice is that the direct replacement harnesses you chose for your Camaro build are manufactured to exact specifications of original GM harnesses. They are exactly how General Motors designed them back in 1969–just 45 years newer without the wear and tear,” explained Yeager.

We aren’t too terribly worried about originality on this car, but we wanted to be able to use the stock harnesses for several reasons. For starters, we can grab any OEM wiring harness and know exactly which wires go where and what they do. Furthermore, the stock wiring harnesses will be the correct length, with correct connectors on it. A universal one would require us to use broken, worn-out connectors and have to cut all the wires to the correct length, eating up valuable time.

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Well thought out wiring harnesses have good color coding, cut-to-length and quality connectors that work with OE-style plugs.

“All our harnesses are reproduced using original General Motors schematics and on top of that feature all the correct attachment connectors. Our harnesses also use the correct wire gauge sizes and colors in order to match the original and maintain authenticity,” explained Yeager. That’s exactly what we were looking for.

Battery Power

Our one-gauge trunk mount battery cable kits are designed for most applications where a project car has the battery located at a distance away from the engine compartment. -Scott Bowers, Ron Francis Wiring

With the wiring harnesses on their way, it was time to figure out putting the battery in the trunk. We know this requires a battery box to keep the battery mounted, along with some heavy-duty cables to handle the load. We knew there was more to it than throwing a battery in the trunk and running some big cables, so we called up Scott Bowers of Ron Francis Wiring to shed some light on the subject.

“Our one-gauge trunk mount battery cable kits are designed for most applications where a project car has the battery located at a distance away from the engine compartment. The kit features high temp crosslink insulated cables and all other items needed for installation, including lugs for the other ends, heat shrink, and even a crimp tool to properly crimp the lug ends to the wire,” explained Bowers. This made the installation a lot easier for us, having everything we needed to accomplish the task at hand.

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Wires and connectors that can handle the amp load are essential in a good wiring job.

“Amp draw or load is what determines proper gauge size. We supply one-gauge as it is beyond what is typically necessary and in just about any situation will be more than sufficient to carry the load,” Bowers continued. With us taking the car to the track, we need to make sure we have the juice to turn over the massive 502 cubic-inches, even when things are hot.

Kits with high quality connectors, heat shrink protection and proper hardware will last a long time and perform well.

One common thing that most people do is run a positive cable, but only run the ground to the frame. This set up works, but is less than par and can be improved upon. “First and foremost, take the battery ground all the way to the engine. Mount the ground on a major engine bolt like at the bellhousing. Then ground the engine and body. What enthusiasts don’t realize is that steel only conducts a portion of what copper can.  If you ground the battery to the frame, you are losing power and leaving your electrical system at a disadvantage,” explained Bowers.

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A fuse box is a necessity. Keeping all of your electrical circuits and components protected is the sign of a good electrical system.

With the cables situated, we only needed a box to hold the battery. There are different styles out there, depending on different styles of batteries along with different regulations for different sanctions of racing. Even though we’re using a dry-cell Optima battery (PN: 8012-021), we wanted a housing so we’d have it protected and so it would pass inspection at any event we decide to go to. We picked one up from Moroso, which is approved by the NHRA, IHRA, and the SCCA. The battery box itself can handle batteries as small as a 21 series battery all the way up to a 96R, giving us plenty of options for Optima battery choices.

Below are some features of the battery that we chose to run:

  • 12-Volt, 750 cold cranking amps
  • Size: 10″ x 6 7/8″ x 7 13/16″ tall, Weight: 42.9 pounds, SAE Post
  • Reserve capacity of 120 minutes for constant performance
  • Optimal starting power even in bad weather
  • Fifteen times more resistant to vibration for durability

Getting Down To Business

With everything here at the shop, it was time to wire up this car. We started with all the wiring harnesses from Classic Industries. Since we don’t have any interior in the car, the factory harnesses were a snap to put in. We started by laying all the different harnesses out; unlike a universal kit, the factory harness is actually compiled of several different circuits that connect to each other.

Working from the back of the car forward, we laid the rear lamp harness inside the trunk, clipping it into the body mounts along the way. With the factory lengths, there was no need for splicing or trimming wires. The new connectors on the ends meant all we had to do was pop them into the taillight housings and we were done.IMG_8300

From here we ran a new front-to-rear harness that lays against the floorpans. We also ran a new dome light harness setup, which plugs in off the rear harness inside the trunk. The next step was to install the dash harness. It helps a ton if your gauge cluster has been popped out, in order to gain access. Making things even easier for us was the fact that we don’t have a heater in this car, giving us even more room under the dash.

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Wire routing is often overlooked but great care should be taken when routing wires near parts like pedals and steering shafts.

Again, this was a plug and play installation where we hooked up the ignition, cigarette lighter, headlight switch, etc. One small note here was that since we are running a Dakota Digital VHX gauge set up, we did have to cut a few wires to feed into the control module for that. Using the factory wiring harness diagram we picked up, it was easy to know exactly which wires we needed.

Under the hood the wiring wasn’t as straight forward. Fitment wise everything fit great, and we had the headlights working in minutes. However for the engine harness, we modified it a bit to suite our LS engine. This means some of the wiring for factory sensors were removed. Not a necessary step, but one we did to ensure a clean installation. It’s still useful to use the factory engine harness and modify it so that it plugs into the factory ignition switch and we can grab power from it. Still an easier solution than a universal cut-to-fit application.

Batter(y) Up!

The time had come to finally deliver some volts to this Camaro. Starting off, we grabbed the Moroso battery box and figured out where we wanted to mount it. There’s a lot of different theories and locations for the battery. We’ve seen batteries mounted just about everywhere, but went with the traditional method of mounting it in the passenger rear quarter panel. This moves the weight from the front of the car onto the rear wheels, and we will need every bit of traction we can get.

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When it comes to wires, it’s not a one size fits all proposition.

Installation is pretty straight forward once you’ve located the mounting position. Two all-thread bolts go all the way from the battery box through the floor, where we had drilled two holes. A few nuts were used to secure everything down, and the battery box was set in place.

From here we had to run cables from the battery to the starter. One final detail Bowers explained on the cables was regarding the insulation. “Be sure to pay attention to the the insulation of the battery cables you are sourcing. We use SXL crosslinked insulation on our battery cables, which is designed for automotive environments and can withstand 255 degree temperatures and is resistant to fuel, oil, etc.” The last thing you want is for cheap insulation to break down, and short out your entire electrical system.

Powered up with information, we set out to run the new Ron Francis cables. With no interior in the car, installation was a breeze. We simply laid the cables along the inside of the trunk, and down the groove under the door sill on the passenger side. Once we had those laid down, we simply drilled a hole in the floor to plumb the cables through to the starter and block.

The Final Extra Step

One extra cable we ran along with the battery cables was a power charge cable for the alternator. This is smaller in diameter, but still more than adequate to handle the power from the alternator. This cable will allow us to run a kill switch, should we decide to in the future for racing events. A great idea for any car, especially ones planning on heading to any sort of track.

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Wire connectors that fit factory style connectors makes the job easier.

With our wiring finished, it was time to finish up the last tid-bits before we hear this monster roar back to life! Be sure to check back for more updates.