Firstly, one needs to remove the wiring from the car. Since youíre doing a complete restoration youíll need to do so anyway. Removal of the two wiring looms is fairly simple if you take your time and watch what youíre doing. Follow along carefully and weíll have the looms out in no time.
After the carpeting and seats are out of the car you will discover a bundle of butt connectors located at the bottom of the "A" post on the left side of the car. The "A" post is the vertical piece that your door hinges mount on. Look at the base of the "A" post just where the carpeting ends. If youíre working on a right hand drive version then your connectors will be on the right side at the base of the "A" post.
The rear loom (which runs to the fuel tank sending unit and the lights at the rear of the car) is removed first. After disconnecting this loom at the aforementioned connectors one can snake the loom out of the car up and over the rear fender well. Prior to removing the rear loom you should tape the connectors together in a bundle. This will prevent one of them from catching on its way over the fender well. This rear loom will wind up in the boot (trunk) and will be removed from there.
We now need to disconnect ALL of the lamps, switches, gauges, etc from under the dash. This is a time consuming process and you should mark the devices so that reassembly is easier. There are two instances where the main loom passes through the firewall (bulkhead) and into the engine compartment. These will need to be disconnected as well and passed back through the firewall to the interior of the car.
Now the fun begins. This is where you can make your life easy or miserable. This portion of your restoration can make things easy upon reassembly. You will need to clean the loom at the very least. Warm, soapy water works well. Remember to allow the looms to dry thoroughly after washing. In some cases youíll need to redo some of the wiring and this can be done with new wire or with connectors. Remember a good mechanical connection is not necessarily a good electrical connection. Use of crimp on connectors by themselves, without soldering, is not a good idea. Most of these are connections that will not receive much attention until they fail, thus they should be done properly the first time.
If itís necessary to replace wiring then do so but do it properly. Use the correct gauge wire. Use a similar color if possible. When done with your repairs rewrap the loom with the correct material. Loom wrapping tape is available from most suppliers.
A trick to try when you're all set to go is to hook your 5 - 10 amp battery charger up at the regular battery cables (without the battery connected) and then test one circuit at a time. Do headlights first, then turn them off and do turnsignals, then try the brake lights and so on. This does a couple of things. It allows you to make sure that your circuitry is sound AND it uses the built in circuit breaker on your battery charger to protect the wiring on your car. If there IS a problem with a bad load (direct short to ground for example) the breaker on the charger will trip and won't reset until you disapply the load.
Most folks who admire your car wonít see the wiring work you have done. Youíll know itís there though. Just another example of the fine work youíve done on your Spitfire.