Discussion Forum - Northstar Chevelle Club

You could go to HID, but really, just Halogen's with direct power via the relay system is a huge difference in light output for less cost. I did this on my '66 and really like it. It's quite inexpensive and easy to do. If you've gone to an internally regulated alternator, you have the room for the relay's on the core support where the regulator was.

I went with bulbs & housings from AutoPal off of EvilBay. They use replaceable H2 & H4 bulbs like a modern car.

Fair warning, this is what would be called a "moderate skill level" upgrade, as it required some minor metal-working and quite a bit of electrical additions. If done properly there won't be any noticeable mods to the metal parts, and the electrical changes can be reversed without damage to the original harnesses.

Note:
The diagram shows a 4-headlight car. Simply eliminate the bulb(s) and wiring for the dedicated High-Beams (inner) if you have a 2-lamp car... '71 and newer.

Metal Working:
- The large holes in the back of the OEM lamp "buckets" were too small. The new bulbs/housings have a large rubber grommet to protect the connections, and they won't fit through the OEM holes. I clamped the buckets to a scrap of wood and using a hole-saw, opened them up to fit the grommets. A nibbler & file would work as well. A clean-up with a file and repaint finished the job.
- There are notches in the buckets to index on lugs molded in the OEM sealed beams. In my case (non-DOT/USA lamps) the lugs molded in my lamps did not match-up to the buckets - the lamps "indexed" about 20 deg's off. Using a Dremel & cut-off wheel, I cut new notches in the buckets at the correct locations. (You may not have to do this with the lamps you choose, but be warned)

Electrical:
The downfall of the OEM circuit is that GM routes and switches power all the way back & forth through the headlight & dimmer switches... on 20ga wire! This is not adequate for today's higher amperage lamps. The following description & diagram will correct this, and modify the existing harness to operate like a modern circuit using relays.

- When complete, the OEM harness will do nothing but supply a +12v "trigger" to 2 relays. One for Low-Beam, one for High-Beam.
- A new main feeder - with 30A circuit breaker - will supply the relays that do the heavy current.
- New feeder wires to the lamps themselves - upsized from OEM - will supply the lamps.

Materials:

Modern headlamps of your choice

20' each of 18ga, black, tan, & green wire

10+' of 14ga red or yellow wire

2) Bosch relays

1) 30A circuit breaker

Misc: Insulated crimp connectors (Female & Male spades, ring terminals), self-drilling button head screws, "star" washers, electrical tape/harness wrap, wire-ties

Sources:

Relay Basics

Electrical Basics (see Ground/Grounds/Grounding)

Crimp Connectors

Circuit Breaker 30A, tab-mount, screw lugs

Relay Bosch 30A, tab-mount

** The parts shown are examples, to show what you're looking for. **

This job will take the better part of a day, you'll have to dis-assemble the headlight assemblies, but the rewards are worth it. Feel free to relocate the devices where they work best on your car, and you can always up-size the wiring a bit (NEVER down). (The gauge of wire shown is fine for the load & distance of the average installation)

*Doing this modification just for your OEM bulbs or Halogen sealed-beams will make a noticeable improvement in output!*

Its actually not as complicated as it sounds. In a nutshell, your using an electronically operated switch which is the relay. The relay is operated by the physical headlight switch inside the car you turn on manually. The relay has a coil of wire inside and using electro-magnet via the coiled wire, energizes a set of contacts that act as a switch that opens and closes or vise versa. 

Basically.

You move headlight switch to on which energizes/turns on a coil of wire and goes to ground.

Coil of wire via the science of electro-magnetizm pulls the open contacts closed like a magnet sticking to the fridge and now power can transfer through. Or, you can go the other way with a set of closed contacts you want to disconnect via opening.

The end result is your using one separate circuit to energize or de-energize a another seperate circuit.

You need this because your using a smaller amperage or voltage(like in cases typically outside of the automotive world) to turn on (or off) a circuit that draws more amps. Modern headlights draw more amps and stock wiring is not big enough to handle that load. Though ill admit I ran halogens in my 66 without any problems, its still not a good idea. Im planning to run a headlight system from a company called Oracle Lighting myself.