This modification upgrades the headlights and adds a relay in both the high and low beam circuits so that the headlight switch, the dip switch, and the flasher switch do not carry full headlight current.

Use two 30 amp relays (e.g. Narva part No. 72386). These are mounted on a home-made bracket attached to the left hand stud holding down the padded dash top behind the centre dashboard swing-down panel.

The main supply to both relays comes from the ammeter terminal to which brown and white wires are already connected. Leave these in place. The outputs from each relay are connected as follows:

• The high beam relay output is connected to the supply side of fuse number 1. This replaces the blue and yellow wire from the dip switch which is disconnected from fuse 1 and instead is connected to terminal 86 of the high beam relay. It becomes the triggering input to the high beam relay. Terminal 85 of the relay is earthed.
• The low beam relay output is connected to the supply side of fuse number 2. This replaces the blue and green wire from the dip switch which is disconnected from fuse 2 and instead is connected to terminal 86 of the low beam relay. It becomes the triggering input to the low beam relay. Terminal 85 of the relay is earthed.

The flasher switch is already connected to the high beam output of the dip switch and no modification is required here. This provides an alternative triggering signal for the high beam relay.

You are now ready to instal a Hella 5604/100 headlamp kit. This comes with 100/90 watt globes. (Cheap alternatives are not recommended).

LET THERE BE LIGHT.... WOW !!

The original Lucas 11AC alternator appears to have no trouble with this load.

I can’t vouch for the capability of the earlier DC generator.

Another related upgrade can also be done. This is to use a redundant wire already in your E-Type wiring loom as a parallel supply to the headlamp high beams. The purpose is to reduce voltage losses in the high beam circuit. The circuit diagram in the workshop manual shows this wire is for “fog lamps (when fitted)”. The redundant wire has a braided cotton sheath which is red with a yellow trace.

One end of the unused wire can be found behind the swing-down centre dashboard panel. This end is connected to the load side of fuse number 1. You’ll find the other end loose inside the nose of the bonnet (i.e. it’s already soldered into the nose-side of the multi-pin plug). Connect this loose end at the nose terminal block to the wires going to the high beams. Access can be gained through the parking lamp apertures and through the opening inside the mouth of the E. (This is one case in which the scrawny are advantaged. The brawny will have to remove a headlamp “sugar scoop” or forego this enhancement.)

A final improvement replaces the old cotton-braided wires connecting the terminal blocks in the nose to the headlights with plastic-sheathed wires. You will probably find that the insulation on the old wires has deteriorated due to the ingress of water. Take this opportunity to upgrade to a higher rated wire. The originals are 14 strands of 0.25 mm wire.