On a 72 Cutlass, with the 4 headlights. Are the high beams a special bulb as they only have a high beam function and not a dual function like the normal driving light does? The driving light has 2 light outputs, a low beam and then high beam. The high beam light only has an on/off but is it a special high beam bulb?

 

Yes. The outside lights have two filaments, a low-beam and a high-beam. Three electrical terminals--low beam power, high beam power, and a shared ground terminal. The inside lights have only one filament, the high beam. Two terminals, power and ground.

Low beam use, only two headlights are operating. High beam use, all four light.

This is not true of later-model vehicles with four "small" rectangular headlights such as an '86 Toronado or '88 K1500. On those, only the inside lights glow on high beam. A common modification is to add a relay so that all four lights work on high beam.

 

So is the separate high beam inner lights a brighter light than the low beam outer set of driving lights?

 

Basically, yes. You used to be able to just go to a parts store or KMart or Sears (HUH?) or somewhere and buy the standard bulbs for your Olds or Ford or whatever. Used to be most cars and trucks had either a sealed beam single 7" light (2)or dual 5" (4)lights. In the 80's you could get them in Halogen to go back and make your car a little brighter. They used the same part # with a H in front. You may have to order them now as I'm guessing most stores don't carry them anymore.

 

A hi beam is always brighter than a low beam, by design.

 

Very few stores even stock sealed beams anymore. Keep in mind that the last time a new vehicle was produced with round sealed beam headlights was over 40 years ago.

 

I recently purchased a replacement Low/High bulb at O'Reilly's.

 

Yeah, the few times I've been in O'Reillys I've been impressed. Unfortunately, they haven't yet made it to Northern VA, so I've only used them on trips (like HRPT last year, and 2016 Nationals in Kingsport).

 

So If I am replacing the high beam with a H4 Hella Projector. Should I get a single filament/bulb LED or a dual filament/bulb LED like I have for the driving lights?

Currently I have the German H4 Hella projectors on the driving lights and it makes a HUGE DIFFERENCE in nighttime driving. A clean 6000K light and lights up the road really nice. Plus the LED bulbs only draw 30 Watts per, instead of the factory bulbs which are maybe 110 Watts?

 

Single to replicate the factory bulb.

 

I've always liked the original Halogens. I wonder if GE still makes them for those years.

 

You can get sealed beam halogens through your local parts store I've been happy with the Sylvania brand sealed beams I bought for my car. The projector beams will usually require rewiring and adding relays.

Your part#'s are
H5001 for high beams halogens
H5006 for low beam halogens

 

The usual problem with dim "original" lights comes down to three things.
1. The reflectors have corroded, light is "leaking" out the back of the sealed-beam bulb. Common as dirt.
2. The headlights haven't been aimed since the vehicle left the factory; but the ride-height has changed and the headlights are no longer aimed where they're supposed to be.
3. Corrosion in the wire harness has reduced the voltage at the headlights. Ideally, headlights should operate between 12.8 and 13.2 volts. Headlights are rated for brightness at 12.8 volts, they're rated for service life at 13.2 volts. Less than 12.8, and the lights are dim. More than 13.2, and they burn-out early. A common "fix" for dim headlights--adding relays triggered by the original wire harness but supplying power direct from the battery or alternator--generally results in 14+ volts at the headlights. They're real bright (for awhile). There should be "0" volts on the ground side. Any voltage on the ground side subtracts from the voltage on the supply side. If you had 1 volt on the ground side, and 11 volts on the supply side--the headlights operate on 11 - 1 = 10 volts.