H4 Headlight Conversion

[Tim Jobson]

In addition to my bodywork tasks I have also purchased new headlights as the current ones have flaking paint inside and out.

When I received my outer lights I noticed that they take a different bulb to my originals which were H1s. As I have not received any advice from Alfaholics regarding this I tried to search the alfabb for an answer but with no luck.

It looks as if the new outer headlights take a H4 bulb that looks to have a twin filament, one for high beam and the other for normal headlights I presume.    Does this mean my original outer lights  only came on for normal headlight operation only and the inners were for high beam?

So I was wondering if anyone in Aust has done this H1 to H4 conversion and could explain what would be the best way to rewire my lighting circuit to suit these bulbs,    that is I presume in addition to installing relays.?

Regards

Tim

[MD]

Tim,

It's been a while since I owned a 105 but I seem to recollect that they had a "cummulative" type of headlight system. That is to say that in the "headlight" mode, the outer low filaments would operate and the inner high beams would simply add to this light in high beam mode. The outer lights never operated a high beam filament.
The cure is to use a double relay for the outer lights so that the high beam filaments are activated by the high beam inner circuit but switch off the outer low beam at the same time. Otherwise you will have two filaments working at the same time at the outer lights overheating and damaging the reflector.
This is a basic loom mod but sould be correctly fused & I do recommend seeing an auto electrician so you don't develop an on board fire.

[alfagtv100 (Biggus)]

Hi Tim,

I found this on the Alfaowner forum.
http://www.alfaowner.com/Forum/the-classic-alfa-romeos/110738-headlight-conversion.html

Cheers,

Marco.

[Tim Jobson]

Thanks for the info guys, I did also find a great article by danielsternlighting who recommended that fuses be placed between the power source and the relays, not as shown in the picture, which seems to make for a better protected system from melt downs!

If my original outer lights were H1s were they also fitted with H4s as standard, it looks like the 1750 had H4s as standard?

Cheers
Tim

[cjheath]

it looks like the 1750 had H4s as standard?

Mine was, it's a '69 (Series 1).

[Tim Jobson]

While studying the wiring diagram for both the 1750 and the 2000, I noticed that the 1750 seems to be set up with the H4 bulbs in both inner and outer lights where as the 2000 has H1s all round.

The 1750 has 2.5mm wire to its headlights and this allows both the outer headlight to work together with the inners when on high beam, whereas only the inner headlights work on high beam in the 2000, and thats probably why it only has 1mm headlight wire.

So why did they take a step backwards with the 2000 headlight wiring and bulb set up....cheaper option?
I am going to rerun at least 2.5mm wire and have it set up like the 1750, with relays that will protect the main switch and fuses to protect against shorts.......has any other gtv2000 owners done this??

Tim

[Colin Byrne]

When I redid the harness for the track car I measured the voltage drop across the standard switch and got up to a 4volt drop across it! So I think the most important thing to do is add relays.  The next thing to do is ensure good earth connections everywhere.  On the track car I ran separate earth lines to all components on top of earthing them to the chassis, the problem with the chassis earths in these cars is corrosion creating bad contacts.  After those two issues have been addressed if and there is still a voltage drop before the lights then look at increasing the wire size. 

[Tim Jobson]

Thats a good tip thanks Colin regarding earth wires.    Did you add a fuse between the battery and the input to the relays?
Also did you reconfigure the lights to operate all four in high beam mode like the 1750?

Thanks

Tim

[Colin Byrne]

Thats a good tip thanks Colin regarding earth wires.    Did you add a fuse between the battery and the input to the relays?

Absolutely

Also did you reconfigure the lights to operate all four in high beam mode like the 1750?

I didn't but the car was never intended to  be driven much at night so there was no need, As for doing it on a road car, I don't see any reason why not to do it, you'll just be putting a little extra load on the alternator, not really an issue

[Tim Jobson]

I have managed to finish the installation of the relays for the main and high beam headlight circuits except for fitting the main outer headlights.

As the origional outer headlights had a H1 type bulb with an earth and live terminal connection the H4s now fitted have three terminals, one I presume is earth, one for the normal beam and one for the high beam.   As I will only be using the outer lights as a normal headlight (not high beam mode as like the 1750 seem to be wired up) can any one shed some light (poor pun) on which terminal on the H4 bulb is the earth and the normal headlight beam?
(the bulbs did not have any markings on the terminals to help identify which is which)

Thanks

Tim

[dfphoto]

Looking at the back of the globe with the middle terminal lying flat at the top, the terminal on your left is the earth, the top terminal is low beam and the terminal to your right is high beam, Thanks David

[Tim Jobson]

Thanks alot David, I will now hopefully light up my garage with a successful test and not become the Prince of Darkness, though that mainly relates to Lucas products!

Tim

[MD]

Tim, all will be fine just be sure never to let the smoke out of the wires  !!