Bristol 403 and Lucas PL 770 headlamps

[Rocket Roller]

Dear all,

As probaly some of you may know, I just bought a Bristol 403 rhd in the UK.

Once I live in Portugal, I'll have to change the headlamps onto right dip
ones, and I was cosidering to get a pair of those glorious Lucas PL770, with
flat glass. The car has others, the smaller ones.

I've been heard that those bigger PL770 simply don't fit later Bristols 403.
By the other hand I also heard they should fit if you change the buckets, or
inner shells.

Any clues?

Yours for longer engine roars,
Joseph
Portugal
(Green 403 reg. UPL 566)

[Des]

I assume you have the 7 inch headlamps, the same as used on almost everything in the past, the bigger flat glass with tripod types you speak of do have entirely differing buckets, much larger, are offered up from behind the cars front panel, then there are a couple more mounting rim / bracket things, mine are dismantled at the moment so will take a picture next time I'm at the workshop, then you can easily see what's needed.
Just a thought, the 770 having no lens, has beam focused by the shaped reflector, these appear symmetrical thus I suspect that there may not be a difference between LHD / RHD, possibly the bulb positioning? Or is dipping to left / right a 'modern' innovation.

[Des]

Here's a pic of the parts that comprise the 770 headlamp assy. The bowl goes on from behind, then a mounting flange goes on front, sandwiching the cars front panel, next, the headlamp, in a chromed retaining rim and big wire clip, lastly chrome outer rim. Quite a few bits to source, same lamps were fitted to Austins, Jaguars, and probably quite a few others. I suspect the light output will be quite inferior to that of a 7 inch unit, the 770 is pre war technology, the 7 inch evolved to the halogen age and is still with us, a version is now available with plano lens, the beam formed by shaped reflector, just like the 770, technology has turned full circle.
I rather prefer the 770, the 7 inch although only slightly smaller, looks too small, my old 401 had 7 inch units cleverly mounted within 770 outer rims, better, but still not quite 'right'. 770's packing halogen bulbs FTW.