Poor headlamp output on a ‘66

[rodneybeauchamp]

Hi all,

 

Am a Buick guy helping out a friend with a nice Springtime Yellow ‘66 Mustang who won’t drive after dark because of the poor headlamp performance. Standard sealed beams at present which should be adequate and changed for Australian road rules.

 

I have suggested relays to improve it but will do the necessary tests for ground issues and voltage drop first.

 

1. Has anyone here fitted relays to a ‘66 that could send some photos?

 

2. Would someone be able to post a wiring diagram as not sure he has a shop manual?

 

Thanks in advance

Rodney 😀😀😀😀😀😀😀😀

[avgwarhawk]

I installed halogen sealed headlamps on my 54 and 60 Buicks.  No relay.  The 54 lights are now fantastic. First time I hit the high beams I couldn't believe the brightness. Nothing went up smoke after driving it with high beams on for an hour. The 60 nighttime driving is much improved with halogen sealed headlamps as well.  I used Wagner headlamps. Amp draw as advertised looked good. I ran with it. 

[Bloo]

Nothing matters as much as voltage at the bulbs.

 

Well, that and the quality of the reflector, but in a sealed beam system there's nothing you can do about a marginal reflector except replace the bulb.

 

[Barney Eaton]

There is a very inexpensive headlight wiring kit available on the internet.   They make the kit for 2 and 4 headlight cars. 

You unplug the existing headlights and plug in the kit connector. 

plug the original connector into the wiring kit. 

attach ground wire in kit to good ground. 

Last... need 12v source for wiring kit.

The advantage is it takes the load off the headlight switch .... with kit, headlight switch picks relays in wiring kit and you get a good 12v source to the headlights. 

It also makes it safer to install halogen bulb or other high current bulbs because the harness is bypassing the headlight switch and old wiring. 

[Barney Eaton]

here is a Ebay link to one of the available kits. 

https://www.ebay.com/itm/124148130601?hash=item1ce7ce2329:g:eggAAOSwHNhej5DM&amdata=enc%3AAQAIAAAA8FaOOk5V6baxKsZxZ%2FoFAgarodP%2FeOkjgeQgVhzgjFSsPt8K%2BnbnhBDRU66MUbfpp4oNB%2FYgCAJDFnykepycNP%2FGLNrWKGfW4E4Nz7umSZAyrWeZRFfJOzdYrPSJH%2BWEUPFqJHmpIByaOaeXEKdOQiPziUrTe57Td1ThylE9Fi6%2FfqSOW%2Bli8wseJvHiwY%2FfMBQ98ct8%2BRHDzkfkPADlk%2BiPIK%2FDy5Y2GhL0vhBwmlG2TCEv%2BGOgLasy33w%2B9AvCtc6kZWW0jDF74DkMDA8NEg6%2BDX1CU%2BZnSa%2FuMrzV%2Bjf8gqNyqBr1G%2FbaW%2B0mbcjBLw%3D%3D|tkp%3ABk9SR5T44qmrYw

[JFranklin]

The original sealed beam headlights were fully adequate when the car was new, I would check the voltage and grounding. If good, 2 new sealed beams might make a difference. I found much brighter headlights after my cataract surgery!

Edited February 3 by JFranklin (see edit history)

[ABear]

On 2/2/2024 at 11:11 PM, JFranklin said:

The original sealed beam headlights were fully adequate when the car was new, I would check the voltage and grounding. If good, 2 new sealed beams might make a difference. I found much brighter headlights after my cataract surgery!

"fully adequate" at the time of build doesn't mean there isn't "room for improvement".

 

The OEM sealed beams at that time "got the job done" and that is about it.

 

OEM sealed beams were standard incandescent filament bulbs, fast forward to the 1980s and sealed beam lamps got an "improvement" with Halogen bulbs entering the market which provided a bit whiter and brighter illumination.

 

I have driven with both in the round bulbs of that period, hands down would prefer Halogen bulb style over standard filaments.

 

But, there is still "room for improvement", the wiring ga of the wire often used is just adequate enough to handle the current without overheating without taking in consideration of the voltage drop over the run.

 

OEM wiring can result in as much as 20% reduction of voltage at the bulb and that results in more than 25% reduction in brightness.

 

That is where adding headlight relays and heavier wire comes in to the mix. A heavy ga wire is run directly from battery under the hood right to the relays and then heavy ga wire is run from the relays to the headlights. This shortens the length of the wire which also reduces voltage drop.

 

There are drop in kits for sale and they don't cost all that much and are plug and play if you get the correct kit for the old style round headlights.

 

You can also DIY your own, the 30A Bosch style relays are pretty inexpensive (Often can be found for $2 each) and only takes two. Add in cost of wire, fuse, connectors and can be had for a bit less than the premade kits. The advantage of the DIY route is you can customize it to fit your vehicle and even completely hide it for show points.