A Guide to Bosch H1 Headlights

Check out our new Guide to H1 & H4 Bulbs

Bulb-H1-HelioThe term H1 actually more correctly refers to a type of halogen bulb, but over time in the Porsche world it has come to stand for the headlamp assemblies using two H1 bulbs. The following information has been gathered from my experience with these fascinating devices and from informative discussions on the Early 911S Registry that I started.

Telling the difference between H1’s and H4’s

It’s easy to identify H1’s vs. H4’s when you know what you’re looking for:


History of H1’s

Here are some historic facts in no particular order:

  • The first halogen bulb for vehicle headlamp use, the H1, was introduced in 1962 by a European consortium of bulb and headlamp makers.
  • Bosch introduced headlights with H1 bulbs in 1966 and headlights with dual filament H4 bulbs in 1971. Strictly speaking that means that H4 headlamps are not correct for SWB cars. Source: Bosch Automotive: A Product History. 
  • H1’s were first offered as a factory option for the 1968 911S beginning with chassis 11800226 (coupes) and 11850065 (Targas) and additionally for 911T’s and 911E’s starting in 1969 (from posts by Registry members citing Bosch and Porsche publications). They were available as after-market add-ons beginning with their introduction in 1966.
  • H1’s didn’t become legal in the U.S. Until 1997.
  • There was one generation, or model, of early H1’s made with city lights in the buckets. These appear to be uncommon.
  • The first LHD lenses were marked …007 with raised letters on the outside of the lens and had a larger prism, with two bars on the top of the prism (1966-1969).
  • The next generation of LHD lenses were marked …010 with raised leters on the outside of the lens and had a smaller prism with one bar at the top of the prism (1969-1972). There is definitive evidence that the raised script lenses were used at least into 1972. Source: Owner of Porsce Parade Concours Trophy winning 1972 911S.
  • The subsequent, and current, generation of LHD lenses are marked …010 with raised letters on the inside of the lens (1973-present)
  • H1’s were made for and used on early VW’s. The chrome trim ring has the mounting tab at the 6:00 position. These had the small bulb “city lights”.
  • There are two versions of the low beam bulb holders, probably a generational change.

Some pictures…

I receive a lot of cores to restore which gives me a chance to take a look at H1’s produced at different times. Here’s a bit of a pictorial history. The earliest lenses, in production for a very short time, had raised lettering on the outside of the lens as opposed to the next generation which had them on the inside, which continues today. The lenses pictured below are very early H1 lenses – note the larger “prism” area as compared to the later lenses. The number of the one is 1305 614 007 and the other is the only one I have ever seen with the number 1305 614 007..008.

old lens old lens 2I occasionally come across H1’s with what are referred to as “city lights”, small bulbs mounted in either the housing or the reflector. These are wired into the parking lights and are great looking. but rare:

city 2city 1

The first generation of lights used a different style of bulb holder for the low beam bulb mounted in the large reflector. The top picture is the old style and the bottom picture is the newer style, the one we’re more accustomed to seeing:

old bulb housing

new bulb holder

Older on the left - Newer on the right

Older on the left – Newer on the right

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