Some brightening when revving with the standard alternator is inevitable,
although some high-output aftermarket units are said to give more output at
lower revs. Some say that they have converted as their alternator was
unable to keep up with headlights, heater etc. at idle i.e. stuck in traffic
and therefore was slowly discharging the battery, but on both my cars the
alternator is able to keep the battery above 12.8v at a minimum. It's true
the V8 has a larger alternator, but then it has twin electric fans and is a
GT with heated rear screen, both of which take quite a bit of current. With
minimal electrical load and about 3k rpm you should have about 14.5v on the
brown at the fusebox. At idle this will drop a bit, and with increasing
electrical load drop further, and should be higher at 3k than idle. You may
also have bad connections at the alternator, starter solenoid and elsewhere
meaning that this voltage gradually drops as you move from the alternator to
the solenoid, fusebox, ignition switch and lighting switch browns.
The standard headlights are also none too bright compared to modern cars,
but if one headlight is dimmer than the other it sounds like you have bad
connections. It sounds like you splice is an extra connection and hence an
extra connection to go wrong, and at 10" from the bucket could be in the
wing area and not behind the grille which is even worse. The headlights
should have longer 'tails' than that to join to the main harness behind the
grille, which although it is still exposed isn't as harsh an environment as
behind the buckets. With one dim headlamp it could be an old bulb with a
lot of silvering inside the glass, or bad connections to its holder, or bad
connections from its tail to the main harness which are a set of three
bullet connectors giving two possible places for bad connections. There are
a set of three, four-way bullet connectors by the right-hand headlight and
as well as the tail for that headlamp connecting here the main harness wires
go into and out of the same connectors giving another two possible bad
contacts for the left-hand headlight. You could take voltage measurements
(headlights on) along the wire from the dip-switch, both side of the
connectors by each headlight, and back of the headlamp assembly (removed
from bucket), on both coloured and ground wires. ideally you should see
full system voltage on the coloured wires, and 0v on the black ground wires.
Lower voltages on the coloured wires and/or higher voltages on the ground
wires means you are losing light output. However another cause of dim
headlamps, especially if you have uprated headlamps, is tired main lighting
and dip switches, which will also drop voltage. With uprated headlamps you
should always fit relays, they will make a huge difference, and I also
recommend individual filament fuses.
For the cost it would be a good idea to replace all these bullet connectors
with new, polishing up the bullets themselves with fine emery, and
assembling to the new connectors with Vaseline etc. for lubrication and
sealing. Make sure the bullets are fully pushed in, they go in so far and
seem to come to a stop, but need to be pushed in a bit more to get the nose
of the bullet over a bump inside the connector to be properly fastened.
I've cut a notch into the end of each handle of a suitable pair of pliers
just big enough to accept the wire and press on the back of the bullet.
With both bullets lightly pushed in to the connector, place the notches over
the wires, and squeeze the handles. Also works in 4-way connectors with a
wire on one side only. However after doing a loom replacement I found that
the copper wire across the front of the car was tarnished for several
inches, and as the bullets are only crimped onto the wire there may be a bad
connection here too.
PaulH.
|