Beam pattern has to do with the lens not the bulb.
Light out put is the bulb and the reflection off the back of the lens.

I had a set of Cibié on an 86 K5 Blazer and I hated the light out put on low beam. Many times I would turn the head lights off just to make sure they were on as you could not tell they were on.
High beam was not bad and 1 of the reasons I did not go back to a normal sealed beam bulb, the other was I was to lazy.
Most of the time that I could use the high beams, back woods roads, I also ran an off road driving light.
So them fancy lights are not always the best thing out there.

For my 81 F100 I am going with "KISS" good old halogen sealed bulbs with the relays and call it done.
Dave ----

 

FF2 -- Do you have a part number for the Kiss Halogen Seal Beams ?

Will they fit & replace my 1971 F250 7" round OEM seal beams ?

What is the low & high wattage numbers ?

 

This what I've been using for over 20 yrs But did try the led crap with the messed up patterns so went back 7" Halogen.
Sylvania 30735 SYLVANIA H6024 XtraVision Halogen Sealed Beam Headlight (7" Round) PAR56.
Orich

 

Old, I think that Fuzz's Kiss Halogen's means Keep it Simple, Stupid using old style halogen sealed beam bulbs.

 

Hey, sorry old28. Didn't see your question until just now.
You can get away with, what you can get away with. But being in So Cal I would think you'd at least try to keep from killing oncoming traffic as much as you can. But yes, the legal limit is 55w (for low beam) but you can buy them literally up to 120w lows! I have set of the old ceramic base PIAA super duper killer off-road H4's that are something like 90/120's or something like that.
In general though, there are commonly available bulbs with 65, 85 and various other wattages on low beam. The difficulty is not burning out eyeballs when using them. And not upsetting a police/patrol member that has some extra time on their hands and wants to make an example of you.
That said, if you get the right lens/reflector setup, you're less likely to blind oncoming traffic to begin with. Then it comes down to how high your truck sits.

No. And yes...
You can change any H4 to any H4. Does not matter what brand or wattage, they are an industry standard bulb that will fit into the housing of any H4 lamp.
What does not happen (much) is changing the beam pattern. Because it's an industry standard, the filament of an H4 bulb (or any numbered bulb for that matter) must sit at the same depth inside the housing no matter who made the lamp. So the beam pattern is supposed to, and for 90% of the time it does, remain the same no matter how many watts, or how many different brands you try.
Because of today's sad state of the aftermarket however, more and more cheap imported brands of bulbs don't quite meed the standard and will in fact change the beam patter slightly. There's just no way to know, nor to control how it changes it.
So your best bet is still to use the best lens and reflector combination you can find for your truck. And that comes down to (usually) the Hella and Cibié brands for now. As I may have mentioned previously, there are other brands too (such as Carrello) that are excellent. The problem is they're very hard to find sometimes. But with the internet in your favor and on your side, you can probably come up with them as well.
Most any brand that sells the rectangular ones will also have the round ones. Again, with the import companies that rely on "cheap" as their goal, that does not always hold true. But the traditional companies will typically have both. From my own testing (admittedly, with only single pairs) stay away from Bosch, Lucas, Cibié "Bobi" (discontinued, but pop up now and then), and even Marchal when you see them. Some of them made great off-road lights, but all the ones I tested in those brands in either round or rectangular (or for a few, both) were horrible beam patterns. Only the Hella and Carello were worth a darn in my testing. The Cibié has held up well from other people's tests though.

Paul

 

Well there's another negative for Cibié then. You don't remember if you had the regular, or the "Bobi" version by any chance, do you Dave?
Reason I ask is that everyone I know loves their Cibié lamps, but the only ones I ever used in my truck were the Bobi model, which was a DOT legal sealed-beam H4.
It still used an H4 bulb, but it had a secondary "bubble" around the bulb, inside the lamp. So the lens and reflector were actually sealed, but you could still change the bulb. Those lights sucked!
But the regular ones have a loyal following, so I was wondering which ones you had.

True words! I tried 9 different brands on my Bronco (7" round), and 4 or 5 on my pickup (rectangular) and hated most of them. But loved a few for sure.

Paul
*

 

If it's made in a 7" round version, it's "expected" to fit. There have been occasions where the older vehicle's light bucket was slightly shallower than typical, or the rear opening slightly smaller, so that a particular brand lamp did not fit without having to modify the bucket.
But since they're supposed to be a standard (just a little looser in the old days) you might find some brands fit just fine, and some don't.
But the relative fit of a round vs a rectangular is going to be different too generally. I don't remember ever hearing anyone with rectangular lights complain about the aftermarket assemblies not fitting. But have heard several over the years with round ones have little issues here and there.

Can't speak for FuzzFace's experience, but from what I've seen, if it's a sealed beam from the normal auto parts sources, it's got 55w lows and 60w highs. That's just how they are because they're meant to be standard replacements and road legal in the US.
You can still find regular lights that have the old school 45w lows and 60w highs, but not as common. And not as good in the light output department.

You'll see some different wattages with modern replacement bulbs, because the regulations are different for them. Like you'll see for example an HB7 with 65 watt or something like that. I don't know the numbers, so that's just as an example.
But legality with H4's, and as far as I know sealed beams, stops at 55w lows.

Paul

 

See the below answer as to what I would run but square to fit my truck.

Yes that's the one. Even the basic bulb is better than their over priced top end bulb that does not last.

Yes that is what I meant of KISS.

I just looked up bulbs for my 81 F100 and I would go for the SYLVANIA XtraVision Halogen Sealed Beam Headlight.
I have 4 basic halogen bulbs to go thru before needing to buy anything just yet.
But I will be wiring in the relays to use with what ever I use.
Dave ----

 

I am not sure what they were.
I have the boxes with the stock bulbs in them some place. I what to say they were DOT but I don't remember if they had that other bump? They did use a bulb that was replaced from the back side, don't ever remember replacing any bulb in all the years I had the truck.
I do know with that type of light / bulb you could get a higher wattage bulb if you wanted to.
Dave ----

 

Thanks guys for all the information. Lots to look up and go over.

For now I need to replace the H4 halogen bulb in my Top Gear Autosport lenes with a brighter H4 bulb that will give me more light on low beam and still be DOT legal. I have checked on two different ones, OSRAM Night Breaker Unlimited and H1 Osram, both are DOT street legal.

 

when, I did the 130AMP upgrade it should helped with the dime low beam lighting just sitting at a stop light.
I'm not sure If, I gained any more brighter after adding the relays into the wiring system..

Orich

 

orich -- I did not see any real brightness improvement by just adding the relay harness, but I am sure it is an improvement to the headlight wiring system.

As I said above think I will try changing my so/so H4 halogen bulbs to the H4 OSRAM Night Breaker Unlimited or the H4 Sylvania Silver Star Ultra. They will fit in my current lens and they are less than $25 for the pair. For sure they will be better than my cheep-0 H4 I have in now.

 

Well you need head lights an I can't see for shxt since having to close one eye when reading or typing.
An those damn bubble flooder's that appear once a person eye once they have had surgery or a new lens put in.

The 130 amp install was really helped help in making the lights much brighter on my head lights at idling at stops at nights.

Like you said I'm sure the relay did a little help but can't really tell when ya do the 130 upgrade first..
Just running some good ground clearance light below the bumper have helped me to see the road much better now that, I have diabetes for the last 18 yrs.
But try to avoid driving at nights having to wear glasses day or nights.

Orich

 

orich -- thanks for the reply. I may install a 130 amp after I try the new H4 bulbs. I want to do one thing at a time.

 

When, I did the 130 amp alternator pickup a newly rebuilt one from pick n pull for like $23 bucks took to auto zone for testing an show good.
I use my dewalt 18v impact to remove the pulley nut. But it may be easier for those who can't whole the shaft pulley is to loosen it while it's still on the vehicle your pulling it from with the belt on it.. It was like a 100% improvement on my head light brightness.
This was my first upgrade an really was enough for me cause was running dual batteries which was needed at one when had the c/o camper on.
But running all those cab lights took a lot out of my 70 amp setup then. I tried not to drive at night tho.
Orich