please bear with me, i'm stupid when it comes to wiring! i plan to rebuild by harness and such as i cannot afford to buy new stuff, besides the obvious melted wires, what do i need to look for, and whats the deal with headlight relays?
No problem. Electrical can be a real mystery until you get a good understanding of it. The watch-outs on inspecting a harness...look for broken wires, weak connectors, split insulation, etc. Basically, places for electricity to go where it should not. Think of a wire as a pipe. It needs to deliver its load to the right place with no cracks, breaks, leaks.
As for rebuilding your harness, make absolutely sure that you are using at least the wire gauge of the original. It may be worthwhile to upsize some of the high load wires such as alternator, etc. If it was 14, make it 12...if it was 12, make it 10. Also, solder all connections. The factory didn't, but you're not a mass production, cost-conscious operation.
A little on relays...let's say, for argument's sake that your high beam headlights are 65W each after an H-4 upgrade. If you have 4 headlights, that is 260W, roughly 22 amps, which is a LOT of juice. That 22 amps has to travel from the battery, through the engine compartment harness, through the bulkhead connector, through the dash harness, through your DASH SWITCH, through your bright switch, back through the dash harness, back through the bulkhead connectorand back down the forward lighting harness to the headlights. Sorry to belabor this but it's worth thinking about. The full amp load for the brights is traveling 20+ feet and through multiple 30+ year old connections. This is a lot of opportunity for things to go horribly wrong...melting wires, overloading connectors, fire, etc.
A relay takes less than 0.5 amp to trigger. You turn on the brights. Now, that 0.5 amp travels the original path from the battery to the dash and back to the engine compartment. Instead of going to the headlights, it goes to the relay and tells it when to turn on. Your 14 gauge harness will never break a sweat on 0.5 amp. Now, let's say you pull a 10 gauge wire from the post on the starter relay and run it to a set of relays under the battery tray. The 22 amps that is required to run the headlights runs from the starter relay to the High Beam relay and then to the lights, roughly 8 feet, and all NEW wire.
WHEW! Sorry if that got long winded, but once you've used relays a couple of times, you'll really get a feel for how beneficial they are. Let me know if I've helped, or added more confusion.
