The FFR wiring harness includes an aftermarket headlight switch, and we mounted it to the frame under the left side of the dash. A fabricated mounting plate riveted to the dash did the trick. We even used a '65/'66 Mustang headlight ID ring from Virginia Classic Mustang (PN IN85, $8.50) with the switch. The single toggle will be our hazard switch. | 
Though we won't need to install them for a while, we decided to assemble the headlights while we had the wiring tools out. The headlight assemblies seat into the plastic bucket shown and require the headlight connector wiring to pass through a small hole in the bucket. After doing so, we added yet more MSD Weathertight connectors to the headlight wiring for ease of assembly and future servicing. | 
If you are using donor wiring, FFR's Roadster kit includes an aluminum panel precut to mount the fuse box from a Mustang. With a little trimming and an extra mounting hole, we were able to use the precut panel to mount the fuse box from the FFR wiring-harness kit. Many people mount the fuse box with a hinge affair for fuse replacement and future servicing. We'll probably add this later. |
Up front, the only electrical items we had to find homes for were the horns and the ignition coil (everything else had a fixed location). The horns were mounted low behind the radiator, while the Mallory ignition coil from our Mass-Flo EFI kit was attached to the driver's F-panel near the engine. | 
Since we decided not to install any sort of aftermarket glovebox or water-based heater in the dash, we used the space behind the dash on the passenger side to mount our Mass-Flo EFI computer, relays, and fuse block. The computer was attached to the dash-support brace with two stainless tapping bolts and a small bracket we fabricated to the lower-dash cross tube. The relays were bolted to the edge of the computer-mounting bracket, and the fuse block was mounted to the side of the dash support. Everything is nice, neat, and accessible. | 
The Mass-Flo EFI system has its own wiring harness separate from the chassis-wiring kit. The harness includes its own plastic convolute and harness tape, though we double-wrapped the harness with extra tape from RJM Injection Technologies for enhanced abrasion resistance. |
The firewall on the Mk III has a large oval opening for the stock EFI wiring from a donor Mustang. For those using a carburetor, FFR supplies a block-off plate. Since our Mass-Flo EFI wiring needs to mate up with the sensors on the engine, we decided to use this hole. | 
However, the harness is much smaller than the opening, and the bare aluminum would easily cut the harness with road vibrations. The answer we found was this oval grommet from RJM Injection Technologies ($10 from its Web site). | 
The grommet fit the hole perfectly and allows the Mass-Flo (or any harness) to safely pass through and seal at the firewall. |
While we couldn't finish the installation of the wiper system until the body is in place, the FFR assembly manual suggests installing and wiring the wiper motor now if installing the optional wiper kit. Florida law requires wipers (check your state's legislation on wiper and washer requirements), so we ordered the wiper kit with our roadster. The wiper motor installs directly to the firewall with the included clamp. We used an RJM Injection Technologies wiper harness ($60 from its Web site) that is preterminated with the proper motor plug. It even features a self-park feature. | 
The FFR chassis harness has a 12-circuit fuse box, and some of the fused items won't be used depending upon how you are building your project. Circuits like CB radio, tach (we used the tach signal from the EFI harness), A/C, and so forth will not be used on our build. We simply tie-wrapped these extra wires so they could be safely tucked behind the dash, but we also added a short length of adhesive-lined shrink-wrap (also from RJM Injection Technologies) to the end of each wire. We squeezed the heated shrink-wrap shut with pliers to seal the wire ends and prevent any circuit shorts. Next month, we'll wrap up our wiring and hopefully tackle a few other odds and ends before starting on the bodywork. | |