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Muscle Car Rewiring

More current for hi-po Sixties' beasts

Muscle cars' popularity never wanes. But as the Sixties become more distant, the high-horsepower cars produced in that era continue to deteriorate. Hot rodders are forever updating and upgrading mechanical components, but they shouldn't overlook the electrical system. In fact, totally rewiring a muscle car with an aftermarket kit can improve both performance and safety: Old, brittle wires can crack or fray and produce sparks, which can ignite an electrical fire. Also, electrical components such as headlights perform best when the wires allow more voltage to flow to them.

Wiring Kits

Several automotive aftermarket companies offer complete wiring kits that are assembled with the shade-tree mechanic in mind. Specific kits for popular cars include the proper amount of circuits for all OE accessories, original-style connectors and plugs, and even cut-to-length wire. For those who want to add additional circuits and update their cars with features such as fuel injection, universal extra-circuit kits are available.

Armed with simple hand tools, a wire stripper/crimper and a spool-full of patience, the accompanying Steps show how anyone with average auto-repair ability can gut and replace a muscle car's wiring. A 1966 Chevelle serves as our model here.

For this job, we chose a basic 18-circuit aftermarket wiring kit. In addition to an OE-style fuse panel and wires, the kit came complete with headlight plugs, tie wraps, an ample supply of crimp connectors, and perhaps most important, an excellent instruction booklet. Individual wires are labeled every few inches over their entire length. Moreover, the instruction booklet clearly identifies, per color (using standard GM wiring color coding), per section, a wire's destination and origin. In addition, complete wiring diagrams are included, making it nearly impossible to lose your way.

Installation Overview

When we evaluated the wiring in this nicely street-machined 1966 Malibu, we found an electric Chernobyl in waiting. When the stoplights would go on, everything else would go dim. Repeated trailer wirings had tangled the trunk wiring harness. And wires and connectors had become as brittle as a Pringle. A total re-wire was in order.

Fortunately, our wiring kit came with all wires pre-connected to the fuse panel, making installation in the Malibu a four-step process:

1. Remove the existing fuse panel, wiring and harnesses.

2. Mount the new fuse panel where the stock panel went.

3. Route the wires in "sections": headlight section, taillight section, ignition-switch section, engine section and so on.

4. Connect the wires, lights, switches, gauges and such.

Before we started, we studied the kit to get a feel for the Section groupings and how we wanted the wires to be routed. Then we read the instructions carefully. This pre-planning avoided any major errors once we began stringing wires. With our Chevelle, we strung the replacement wires along the same routes the original ones traveled.

Basic Wiring Tips

> Tying One On: When routing wires, if plastic split loom isn't used, place nylon ties every 2 to 4 inches to make neat wire bundles. Not only does it look trick, this eliminates the possibility of wires rubbing through the insulation, causing a short.

> Support Group: Never rely on the wire's end connector to support the weight of the wire. Use an insulated metal or nylon clamp to support a wire to stop any vibration that could cause the connection to fail.

> Crimp Connections: Some wiring pros rely on soldered connections protected by a heat-shrink insulation. Good choice, but a labor-intensive one. Standard crimp connectors can work just as well as soldered connections and are less prone to breaking or loosening by vibration. The key to crimp connections is to use a proper crimp tool and to not over-crimp the wire.

> Hole Job: When running wires through a panel, such as a firewall or an inner fender panel, always use a rubber grommet to protect the wires. The knife-edge of a sheetmetal hole can, when propelled by vibration, easily slice through wire's insulation. Also, if a wire or battery cable comes anywhere near a frame rail or potentially sharp edge, cover it with a short length of heater hose or vacuum tubing.

> Take Your Time: Take a slow, cautious approach to installing a wiring kit. Measure everything twice. Double-check all connections. Consult the instruction booklet and wiring diagram often.