There’s no worse feeling than sitting at a cruise night or car show and not having your car start when it’s time to leave. Scratch that. A worse feeling would be having your car just shut off periodically for no reason while you’re driving. Our classics or 30, 40, and even 50 years old, and electrical gremlins caused by a bad wire harness can wreak havoc on a car owner. For that reason, I thought we would focus this week’s Throwback Thursday on Project Blank Slate: Making Shocking Connections.

Old wiring is always plagued with shorts and splices. The electrical system on a classic car is similar to the human body’s nervous system — it’s what makes everything happen. The juice controls everything from the movement of the starter Bendix 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 a rolling body to a full-on operational car. Without it, there’s no spark for the combustion cycle, no fuel pump to feed the engine, and no headlights to see at night.

A fuse box that is not rusted or broken is a necessity. Keeping all of your electrical circuits and components protected is the sign of a good electrical system.

In the original article, we reached out to Classic Industries to seek their knowledge about wiring options, Ron Francis Wiring to get more information about a trunk-mounted battery cable kit, and Moroso to secure a battery box.

Ray Yeager of Classic Industries first gave us some information on the wiring harness. “We offer a stout range of replacement wiring harnesses. One thing that’s nice is, the direct-replacement harnesses you chose are manufactured to exact specifications of original GM harnesses. They are exactly how General Motors designed them, just newer without the wear and tear.”

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

When talking to Scott Bowers of Ron Francis Wiring about the battery cables, he states, “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.”

We actually learned something else while assembling this article. Many enthusiasts only run the ground to the frame when mounting the battery. This works, but is less than optimal and can be improved upon. “First and foremost, take the battery ground all the way to the engine,” explains Bowers. “Mount the ground to a major engine bolt — like at the bellhousing. Then ground the engine and body. What enthusiasts don’t realize is 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.”

There’s a lot more in-depth information in the original article, and for that reason, I selected, Project Blank Slate: Making Shocking Connections as this week’s Throwback Thursday showcase article.