All,
I bit the bullet and converted the Midget to the GM 7127 unit. I believe I
used a '78 LaSabre as the PC lookup in the auto parts store. The 7134 also
works, but is an 80amp unit versus the 63amp unit I bought. It was $40
more.
Parts needed:
1) Alternator - 39.99 plus 15 for the core charge. It's a lifetime
warranteed DuraLast from AutoZone.
Note: I got the one with the 12 o'clock harness position and double
pulley. The single pully unit was $20 more. Don't know why.
2) The GM alternator harness plug was 2.39 in the wiring section.
3) 7" chrome alternator bracket
4) 2 wire connectors (blue for medium sized wires) to connect two wires.
5) One yellow (large) wire connector with a circle connection for mounting
on a stud on the alternator.
The methodology:
1) Removed the old alternator and both brackets.
2) Install bottom alternator bracket from a '75 spitfire. This is the same
as the '78 Midgets, only the portion that mounts to the alternator
on
the '78 install is removed. This is essentially a brace. Picture
the
solid piece with the 2 bolt holes for the block, and the 1" thick
hole
that mounts to the front engine plate. The 3" long hole where the
old
alternator fits was never cast on this bracket. I think it had
something
to do with the air pump.
3) Grind off the small lip on the bottom of the GM alternator. You'll see
where it interferes with the front engine plate. I used a Dremel
and 3
heavy duty grinding disks. It's a clean enough job that no one will
notice if I ever have to return it. A hacksaw would have sufficed.
4) Mount the bottom of the new alternator to the front of the engine plate
opposite the bracket you just installed. One bolt goes through the
alternator, the engine plate, and the bracket.
5) Take the old top alternator bracket to the workbench. Cut off the round
loop section that was previously used to pull the engine. I'll have
to
find another method when I have to pull it for the clutch. Also
trim
the bend where it interferes with the water pump housing for the
method
I needed to install it (see below)
6) Replace the old bracket backwards so that the bend which previously
moved
the adjustment section of the bracket towards the front of the
engine bay,
now moves it towards the back of the engine bay (but still pointing
towards
the driver's side of the car (left hand drive).
7) Install the 7" bracket to the alternator mounting hole on the top.
Install it to the old top bracket. They should line up perfectly.
Install
the stock belt, tighten it to spec, and tighten all the bolts.
8) Cut off the old Lucas alternator harness. Leave about 2" of wire on the
harness in case you ever use drugs and want to reverse this
conversion.
Note: My harness had three wires. A small gauge solid brown wire,
a small
gauge brown and yellow wire, and a large gauge solid brown wire.
"The large
Brown wire is the main charging lead. The smaller Brown wire
measures the
system voltage to tell the alternator how much to charge. The
Brown/Yellow
wire operates the alternator warning light, and provides the initial
voltage
to the alternator to start it charging when the engine first
starts," (Dan
Masters).
9) Connect the brown and yellow wire to the #1 wire on the harness plug.
The wire number is marked on the alternator, and the plug is keyed
so it
can only be installed in one direction. Connect the small solid
brown wire
to the #2 wire on the harness plug. Connect the large solid brown
wire to
the yellow connector, and bolt the yellow connector to the stud
protruding
from the back of the alternator housing. The alternator come with a
nut to
bolt the wire down. Make sure you use dielectric grease on the
connections
to prevent corrosion.
10) Make sure all the bolts are tight, all the connections are done, and
that the
belt is tight and lined up correctly with the crank and the water
pump. It
should be.
11) That's it. Start the car, hook up a volt gauge, and see the system
charge at 14 volts.
My blinkers (which had all the switches and connections cleaned a few weeks
ago) now go "click click click click click" rather than
"click...........click..........click....."
At night with the lights on, the radio on, the wipers on (fast), the vent
fan on, and the hazards on I still had plenty of charging power. Nice.
Very nice.
Michael
'78 Midget
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