The headlamp assembly comprises outer bowl, inner bowl or body, light unit, retaining rim, bezel, gasket, loom, and fixings, each available separately. Both cars use 7-inch headlamp units, the MGC using the Lucas F700 Mark X type shared with the contemporary MGB Mark II. Regional variations existed for different lighting regulations, home market UK cars using asymmetric dip beam units conforming to British standards while North American cars were fitted with sealed-beam units to meet US requirements.
Light Units & Specifications
Sealed beam units are available in multiple specifications, 60/45-watt for GHN3/GHD3 cars, 75/50-watt for GHN5/GHD5 cars, and for rubber bumper cars to September 1976. H4 halogen headlamp assemblies became standard on the MGB from September 1976 in 60/55-watt specification. The 7-inch format also accepts halogen and LED conversion units that fit directly into the existing bowls with no modification, keeping the external appearance original while transforming the light output. A halogen conversion uses a standard H4 bulb in a replacement reflector providing approximately three times the output of the original tungsten unit, while LED units provide even greater output with a crisp white light and virtually unlimited bulb life.
For any car driven at night, a halogen or LED conversion is one of the most worthwhile safety improvements available. Complete H4 conversion kits are available for chrome bumper and rubber bumper RHD and LHD cars.
Bowls, Rims & Beam Alignment
The outer headlamp bowl is the chrome-plated housing that locates in the front wing aperture, available in two metal specifications, with the inner bowl or body in metal and plastic carrying the adjustment screws for beam alignment. The retaining rim holds the unit within the bowl, the bezel provides the chrome surround, and the gasket seals the bowl to the wing aperture, with chrome inner retaining rims, bowl-to-body gaskets, and the headlamp finisher rim in reproduction and OE specifications all available. Beam alignment should always be verified after any lamp replacement or front-end panel work, as incorrectly aimed headlamps are both an MOT failure point and a genuine safety hazard to oncoming traffic.
Looms & Relay Upgrade
Headlamp looms for chrome bumper, pilot, and uprated applications are available. The headlamp relay kit is strongly recommended, as the full current draw through the standard switch contacts causes pitting, corrosion, and the idling flicker common on older cars, eventually leading to switch failure. The relay kit routes supply directly from the battery for brighter headlamps and significantly longer switch life.