Thanks Jim for all the info. My '68 el Camino looks like like it still has original T3's. When I was re-doing the grill and headlight bezels, one of the low beams stopped working (hi-beam part of that bulb still works). I also noticed that all the bulbs were somewhat "foggy", so I looked around and found a set of 4 bulbs (2 low & 2 high beams) that are halogen (not T3's), tech spec's say that the the low beam has 35 watt output and the hi beam has 50 watt output.
I tried looking up the spec's on the original T3's in some of the books ( Assembly Manual, GM sales brochure, etc...) but did not see any info on wattage.
Seems like new halogen bulbs should be higher than the 35/50 watts?
Your info is interesting, would like to see if I could get more voltage to the headlights, but all of my '68 is pretty factory stock, still has the correct alternator, so not sure how I could go about increasing the voltage to the headlights easily?
If you ever do come across the specs, please post them.
The specification you have on these 35/50 watt bulbs, do they give you any input voltage to get these 35/50 watt results ?. Anytime you have a wattage rating, you also need to know the input voltage. For instance if you buy a 60W bulb for a house lamp it might be brighter or dimmer at your house than at your neighbors due to how much your house has as far as voltage compared to your neighbors. If you have 120VAC a 60W bulb will be so bright at your huse but if you neighbor has 110VAC then this same bulb over there will be dimmer.
Anyway, on my 68 when I first got it and drove it at night I commented that "boy the dash and headlights are really bright for the age of the car" and I later found out why the aftermarket radio failed and why the lights were so bright. I got out my Fluke meter and measured right about 16.5 volts output on the alternator and at the battery. No wonder things were so bright. I then adjusted the original points type of voltage regulator to where now I'm getting right around 13.5-14.5 volts at the battery. I too also have my original 37A alternator.
On my 68, it's a low mileage car and the wiring is in real good condition as well as the connectors and I would have to look for the info, but it seems to me I measured the voltage at the battery and then at the headlight plugs and I had some drop which is normal but nothing jumped out at me as it being too much of a voltage drop.
A thing you could try is to turn on the headlights (ideally at night) and then with a fused 10-12 gauge wire off of the battery or horn buss, go from there to one of the headlights and see if it gets brighter and if this is how you might like them to be. If it's a minor increase in brightness, then adding relays may not be worth it but if it makes a night and day change, then you could add the relays or dig into the wiring to see how connections are up to the headlights. Keep in mind too that the headlights may be grounded to the radiator support and if the radiator support itself is not grounded well (or even the connections to the support is not good) to the rest of the car and the battery, then this can make the headlights dimmer. I have seen very stealth headlight wiring upgrades to where a person has bought or made connectors to plug into the original headlight plugs and then do the same to have the new wiring terminate into factory appearing plugs to go onto the back of the headlights. The relays are then buried under the fender and the main power for them connected at the battery junction block by the battery fusible link.
One thing you will see in my album with the tests is how bright or dim the different headlights were at different input voltages BUT they are laying on top of a piece of carpet. I wanted to do an actual tests with them being in the car and then having a light meter so far away and at a certain height but I'm still lacking a light meter to do these tests.
If I look at the results I had in my earlier post and then take away the reproduction T3, I can see the following:
The most wattage on low beam with anywhere from 11V-14.4V input is the Original T3 and the Wagner Halogen is not as bright BUT on high beam, the Wagner Halogen has more wattage.
I can say too that with my tests, the reproduction T3's were better in every respect to the original T3's and the Wagner Halogens on both low and high beam and at every voltage between 11V and 14.4V.