In a message dated 98-10-16 09:10:56 EDT, Jjcousins@ra.rockwell.com writes:
> Therefore, maybe it's time to just do the GM alternator conversion. I have
> looked at the VTR pages a little on this subject, but there is not a
> Spitfire page. There is a GT6 page - can this be the same for the Spit?
>
> Anyone ever done this? PLEASE WRITE BACK SOON if you have any ideas!!!
John,
I can help with the electrical portion. Maybe some one else can provide
details for the mechanical mounting details.
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ELECTRICAL INSTRUCTIONS FOR REPLACING THE ALTERNATOR WITH A GM ALTERNATOR IN A
SPITFIRE MK IV, SPITFIRE 1500, GT6 MK II, or GT6 MK III
METHOD ONE (Utilizing existing wiring):
-----------------------------
AT THE STOCK ALTERNATOR:
You will find either a five wire or a three wire connector. If you have the
five wire connector, you will find a large Brown wire, a smaller Brown wire,
and what appears to be three Brown/Yellow wires.
What appears to be three Brown/Yellow wires are actually only two. At one
terminal, you will find two Brown/Yellow wires, and at another, you will find
one. The single Brown/Yellow wire actually goes into the harness for a very
short distance, and then turns around and comes back out, where it connects to
the terminal with another Brown/Yellow wire. If you pull on the single
Brown/Yellow wire, it will pull out of the harness, and you will see what I
mean. You may have to loosen the harness a little bit to get it to pull out.
That short piece of Brown/Yellow wire is to be discarded.
If you have a three wire connector, the short piece of Brown/Yellow wire has
already been removed, either by the factory on the later models or by a
previous owner when he replaced the alternator with a later unit.
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.
FOR A FIVE WIRE CONNECTOR:
Discard the short Brown/Yellow wire, as above. Cut off the terminals from the
Brown wires. On the back of the GM alternator, you will find a large screw
type terminal, and in the side of the body, you will find two recessed male
spade terminals, labeled (1) and (2). When you buy the alternator, be sure to
get the plug that fits these terminals. It will come with short wire leads
already attached.
Connect the Brown/Yellow wire to the lead coming from position (1) of the plug
(the plug is polarized, so it will only go in one way). Connect the small
Brown wire to the other terminal (2). Connect the large Brown wire to the
screw terminal. Insert the plug, and you are finished.
FOR A THREE WIRE CONNECTOR:
As above, except the short Brown/Yellow wire is not there.
Of course, disconnect the ground lead from the battery before proceeding with
any electrical work, and follow all the rules of proper wiring practices. I
recomend using solder connections, and covering them with heat shrink tubing,
but crimp type connectors will work quite well also. You will need butt
connectors for attaching to the plug wires, and a large ring connector for the
screw terminal. If you would prefer not to have splices, you can remove the
terminals and the wires from the plug. Using new terminals of the proper type,
connect directly to the existing wires and insert the terminals into the plug.
New terminals can be purchased from British Wiring, (20449 Ithaca, Olympia
Fields, IL 60461, 708-481-9050) and The Wire Works (167 Keystone Road,
Chester, PA 19013, 800-292-1940), among others.
There are two things, however, to be aware of:
1) Triumph did funny things when they built these cars, so your car might not
match the configuration above, and it may well have been modified by a
previous owner.
2) You now have an alternator capable of twice the output of your old
alternator. The wiring in these cars is only designed for the lower rating of
the stock alternator. If you add heavy loads, driving lights, high power
stereo, etc, you can exceed the capacity of the wires. Also, If you let the
battery discharge completely, the alternator can possibly recharge with enough
current to overload the wires. If your battery is completely discharged,
recharge it with a charger rather than push starting the car and letting the
alternator recharge it. Under all other usages, the wiring should not present
a problem. The main advantage of the higher output is the ability to provide a
higher charge rate at low RPM and idle. The standard loads on the Spitfire and
the GT6 do not require a higher charge current at normal engine speeds, so the
alternator will not be called on to provide enough current to overload the
wires.
METHOD TWO (Upgraded wiring):
If you wish to upgrade the wiring to take advantage of the higher output, it
is really quite simple.
--------------------------------------------
AS ABOVE, EXCEPT:
Disconnect and remove (or cut both ends off, or insulate and tie back) the
large Brown wire from the alternator to the starter solenoid. Replace this
wire with a very large (10 Ga or better, preferably 8 Ga.) wire, running from
the screw terminal on the back of the GM alternator to the terminal on the
starter solenoid. Leave the other existing wires on this terminal as found.
Very carefully route the wire, as much as possible along the existing wiring
harness, and support with the liberal use of cable ties.
Now, the alternator can provide full charging current without worrying about
burning up the wiring.
If you wish to add extra loads, such as a high power sound system, connect
them directly to the battery connection at the starter solenoid, properly
fused, of course.
OPTIONS:
--------------------------
You may wish to add a voltmeter. If so, simply connect the plus terminal of
the voltmeter to any convenient green wire, and connect the minus terminal to
a good ground point. One side of the illumination lamp inside the voltmeter
should be connected to the most convenient Red/White wire, and the other side
should connect to a good ground point (Unless the lamp is grounded to the
meter case. If it is, ensure that the case is properly grounded to the metal
dash structure).
You may also choose to use a different alternator, rather than the GM unit. If
so, it will be wired very similarly to the above, only the connections at the
alternator itself will be different.
Dan Masters,
Alcoa, TN
'71 TR6---------3000mile/year driver, fully restored
'71 TR6---------undergoing full restoration and Ford 5.0 V8 insertion - see:
http://www.sky.net/~boballen/mg/Masters/index.html
'74 MGBGT---3000mile/year driver, original condition - slated for a V8 soon
'68 MGBGT---organ donor for the '74
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