Lancia Motor Club

I am about to re-fit the headlamps to my S1. Currently the outer lamps are fitted with H4 bulbs and the inners old-fashioned Duplo bulbs. Neither seemed very bright before the car was dismantled but I am hoping the improved earthing of the car during re-assembly will improve them. I have noted the conversations about fitting relays elsewhere on the forum but have not yet done this. My question is; which filament in the three prong Duplo is activated when full beam is activated and would fitting a H4 bulb to the inners work in the same way? I have purchased some adapters which would enable the fitment of H4 bulbs to the inners but can see no way of fitting a H1 bulb. Thankyou.

Hi Simon . I got over the problem of abysmal lighting on my 2000 Coupe by buying 4- 53/4" H4 headlamp units and wiring up by doubling up the relays for the near side .  I now have 4 x 55w on dip beam and all 8 filaments 4 x 55w  plus 4 x 60w   (yes 460 watts in total) on main beam. The warning light glimmers at low speed on main beam but at least I can see where I am going  .  To keep it all looking right , I removed all the glasses and siliconed the old Carello ones back on to the new H4's .  It was about 4 years ago but if I remember correctly the 4 units including bulbs cost me £44 total plus a couple of old relays , an extra fuse box and some wiring . The difficult bit was separating the old glasses from the reflectors without breaking them. Another small advantage is that it now has 4 sidelights instead of 2 .  All non-original but I would rather see and be seen .

Thanks Derek, I shall at some point replace the lamps but for now I just want to get the thing back on the road. I probably didn't phrase my question clearly though; how does a H4 or Duplo 3 prong bulb work when connected when connected to a 2 pin connector block?

An H4 has two filaments. one main beam, one dipped.  The third prong is earth.  You choose which of the two filaments to connect to but cannot have the H4 operating Main and dipped only main or dipped.   As I understand it the Series 1 Fulvia has a pair of dipped bulbs, permanently on and a pair of three prong main/dipped bulbs.

It can't , you need a 3 pin connector (readily available on eBay.) and a 3rd wire for both filaments to work

I think I have answered my own question. According to various web-based 'experts' the two opposing prongs on a H4 are earth and main beam, the other prong (at 90 degrees) is for dipped. This would explain why my lights worked. My S1 is wired so that the inners, along with the outers, come on when main beam is selected, and off when dipped.

That is correct....

On a similar note how do LHD lamps differ from RHD. Is it the glass or the mount? Is there enough adjustment if the wrong ones are bought?

Inner driving light is the same. Outers throw a different beam pattern (shown in all Haynes manuals....) RHD kicks up to the left on dipped and visaversa. MOT fail.

Which is why you need to be cautious if buying second hand units , they may be from an unchanged import with RH dip