This article is one in a series that have been released in conjunction with Wayne's book, 101 Projects for Your Porsche 911. The book contains 240 pages of full color projects detailing everything from performance mods to changing your brake pads. With more than 650+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any Porsche 911 owner's collection. See The Official Book Website for more details.
The standard USA-spec headlamps that the 911s ship with leave much to be desired. Semi-outdated US specifications for headlamps means that the stock 911 has a somewhat weak pair of headlamps. Combine that with the 911s need for speed, and you may have a dangerous combination on the road at night.
One of the most popular and easiest upgrades for your 911 is the installation of the H4 headlamps originally used in the European cars. In Europe, most driving is done on country roads, where the high beams are used normally, and the low (or meeting beams as they are often called), are only used when 'meeting' another car on the road. These headlamps have a better focused beam, and also a much brighter bulb. The bulb for the H4s is also replaceable, unlike the US units, which have sealed beam assemblies. Be aware that in some states, the H4s are indeed illegal. However, most states have been very lax in enforcing the regulations, since newer technology such as the Litronic headlamp kits are slowly changing the specifications.
The reason that the US-spec headlamps are required to be a sealed beam unit dates back to a specification in from the 1930s. This law mandated that all cars must have the sealed beam unit because it was thought that water could get within the assembly, and corrode the reflective backing surface, making the light less bright. Obviously, this is somewhat outdated, but has only been changed recently to reflect changes in technology. Also, the H4 is not legal because the DOT adjusting knobs are missing and the glass in not fluted per DOT regulation
The H5 headlamps were also a semi-sealed beam unit that was used on the 911 in the late 1980s. Despite the fact that the number five is greater than four, these are not considered to be superior to the H4s. The H4 is still hands down, the best headlamp that will fit your 1965-89 911.
All 911s thru 1989 can use the H4 headlamps, however, the 1987-89 911s require a wire harness adapter that will mate with the bulb. The headlamp bucket and fender that hold the housing are identical across all these years.
The first step in installing the H4s is to remove the older, sealed beam units. The headlamp ring that covers the headlamp unit is attached with a single screw at the bottom of the unit. Remove this screw, and the cover should simply slide off. The sealed beam assembly is attached to the car by four screws. As you remove each one, be careful that they don't fall down into the bucket, as they can easily escape into the drain hole at the bottom.
Once you have the headlamp bucket removed, unplug the harness from the bulb. The new H4 assembly fits inside the fender opening without any modifications. Place the halogen bulb in the new assembly, and make sure that it is attached firmly with the two metal spring clips. Be careful not to touch the bulb with your fingers, as there are oils in your hands that will create hot spots on the glass, and make the bulb burn out much quicker than normal. Use a paper towel or tissue when handling the bulb.
The assembly itself is attached to the fender by the one screw at the bottom that used to hold on the headlamp ring. Place the assembly into the fender, and make sure that the wire harness is folded out of the way. There should be a slight edge at the top of the fender that the top of the H4 assembly will 'clip' into when tightened. Make sure that the assembly is properly installed onto this clip when you tighten the screw at the bottom. You should be able to pull on the top of the assembly without having it move. Also make sure that you also install a new headlamp seal around the interface between the assembly and the fender.
When you have completed the installation, you will want to adjust your headlamps so that they point the light in the right direction. Park the car on a flat surface about 25 feet from a garage door or wall. Then adjust the vertical adjustment until the beam hits the wall at about the same height as the light bulb on the car. Then adjust the horizontal pointing of the beams so that they are skewed just slightly to the right. To adjust the horizontal and vertical alignment of the beams, turn the two screws embedded in the rim of the headlamp assembly.
The H4 assemblies change the outer appearance of your 911. Some people don't care for the look of the H4s once installed, so make sure that you appreciate the new look of the lamps before you install them.
This photo shows an H4 unit, headlamp seal and a halogen bulb. Sometimes the bulb will come with the unit, and other times you might have to purchase it separately. It's also a wise idea to replace your headlamp seal when you install the new assembly. These assemblies are available with either chrome or black trim (chrome shown in picture). The black trim can be painted to match your car for a smoother look. The chrome units usually look better on the 1973 and earlier cars because they will match the chrome trim on the rest of the car a little better.
Installation is pretty much a snap. Simply remove the old sealed unit and assembly, and place in the new H4s. The harness plugs directly into the bulb, which is supported within the assembly. Make sure that you don't touch the glass surface of the bulb with your fingers.
This photo shows the final H4 assembly installed. Although you get a lot better lighting from the H4s, some people don't like the look of the assembly on the front of the car. The older sealed beams have a distinctive classic look that you may not wish to part with. It's wise to check out a variety of cars with and without the H4 headlamp to make sure that you want to make the switch.