How do you wire a car when no harness exists?

Update by Tim Suddard to the Elva Mk VI project car
Oct 10, 2024 | Elva, Wiring, Elva Mk VI

Photography by Tim Suddard

Before we removed our Elva’s body to complete welding, we thought it would be a good idea to further study our electrical system. What needs did we have regarding lights and other electrical components? And where to find a wiring harness for our Elva Mk VI sports racer?

We decided to start with an early Austin-Healey Sprite and sourced a replacement wiring harness from Moss Motors.

Why a Sprite? It’s a simple car from the same time period so, in the end, it should look period correct. Sure, the Elva has its engine in the rear, but we figured that we could easily modify the Sprite’s harness as needed. (Again, it’s a simple harness.)

Why not start with the harness from a rear-engine car like a Lotus Europa? We didn’t want to deal with the complexities like the wiring for power windows.

Why not a modern harness? We did take that route on some other projects–including our Triumph TR3 and Ford Mustang. Installing a modern harness would have made things simpler but, again, we wanted to restore this Elva to concours-correct fashion.

We started by listing the electrical systems and components that we’d need. As this was originally endurance race car, we needed lights for night racing, including number panel lights.

We also needed the road equipment required back then by the FIA, meaning turn signals and a horn. While not required for modern vintage racing, we needed to keep the car period correct. Plus, it would be nice to have this gear for a quick run to a local cars and coffee or for the street exhibitions at Watkins Glen, Pittsburgh or Put-in-Bay.

[Put-in-Bay Sports Car Races: Annual tradition on a Lake Erie island]

Our buddy Tim Murray is really good on wiring, so we enlisted him for help. We first spread the Sprite harness out on top of the car to see how it would fit. The answer was quite well.

We then looked at all of the required needed: Lights for the side numbers, a charging system (many race cars used just a magneto), head lights, horn and even turn signals were discussed.

Now we could chase down the last items needed to finish our Elva’s charging system, including rear light lenses, a period-correct-looking master kill switch and an alternator disguised as a period-correct generator.