Here's some stuff from my book that might help...
Fred Sisson
First Read the section on generator capacity (in the Generator section) and
you will understand why the old generator is marginal.
Of course all modern cars use alternators and here are many reasons. The one
that convinces me, as a Morgan driver, is reliability. Yes, I have a
generator on the trike- cuz' you see the engine (no bonnet side panels) and I
don't drive it everyday. However many trikes with the generator mounted on
the transmission, have been converted to alternators!
Here are some reasons that might sway you towards an alternator conversion.
Greater capacity.
The standard off-the-shelf GM 10SI alternator puts out 63 amps. You can
buy one converted to 100 amps. You can also buy a kit to convert the 63 amp
unit to 100 amps for around $15.00 US (JC Whitney)
Money!
The GM 10SI alternator runs around $30.00 to $50.00 US at auto parts stores.
Many have a "Lifetime" guarantee.
This alternator was used from 1973 to 1985, millions of cars, so
availability is never a problem. Conversion and wiring is dead simple. I have
them on my Morgan, LandRover and 181 VW.
There is no difference in American, German or British electrons. These
alternators work fine on just about anything that you can mount them on.
Low RPM Charging
Alternators charge at a very low RPM. Usually, even at idle speeds. This
means that you can run good headlights, a radio, maybe an electric fan on the
radiator, and a heater, and the wipers... in stop & go traffic. Worry free.
Longer battery life
Car batteries last longer when maintained at a constant state of
charge. Constant discharging and recharging kills the battery and this is
just what a generator system does as it produces practically no current at
idle. Stop-and-go driving, short trips, electric fans, driving lights, etc.
all discharge your battery quicker than your marginal generator can recharge
it. Over a period of time your battery can get lower and lower. All the ups
and downs shorten the battery life drastically.
Have you noticed how batteries seem to last a long, long time in today's
cars? The reason is the alternator! A good alternator can put out over 80% of
its current rating at engine idle speed. This means that it can provide as
much current at idle as your lights etc. draw. The battery is subject only to
very minor discharge/charge cycles (primarily from starting).
Better lighting
Your lights don't dim at idle, battery lasts and lasts, the alternator
is super reliable, and... the proper voltage also means that your entire
electrical system operates at design voltage.
Less electrical failures- throughout!
All of your electrical components last longer when proper voltage is
maintained. A great majority of the famous British electrical component
failures are simply due to the way the old generator systems allow the
voltage to fluctuate. Low voltage means higher amperage, and high amperage
means more component damaging heat and arcing within the switches.
ALTERNATOR WIRING
The only logical type of alternator to use for a conversion is one with
a built-in regulator. The GM 10SI 63amp alternator is a time-proven design.
They have been used for years on a variety of GM cars and are available
rebuilt... even with a "lifetime guarantee."
The wiring for a GM alternator is dead simple- two wires. One heavy
(10GA) wire runs to the battery. The second wire goes from the ignition
switch, through the indicator light, to the alternator.
Bob Nogueira has devised a way to modify an old regulator and this
allows you to use the existing Morgan wiring. The advantage is that you can
re-install a regulator and generator if you ever desire to return the car to
"stock". If you are wiring your car from scratch and are planning to run only
an alternator, then you don't need to mess with the "modified" regulator.
Just wire according to the diagram.
ONE WIRE ALTERNATORS
There is also an alternator available that is automatically energized
when it reaches around 1200 RPM. The only connection is one 10GA wire from
the alternator to the battery. For a race car these work fine as the idle
with a hot cam keeps it in the charge mode.
For a car that is driven on a regular basis I would still recommend the GM
10SI. This standard (two-wire) alternator will charge at very low RPMs (600
RPM idle) and therefore is better for cars. You also have the advantage of an
indicator light on the dash.
100 AMP ALTERNATOR
The internally regulated General Motors 10SI alternator is produces 63 amps
and is adequate for almost all use. If however, you are running a lot of
auxiliary lights, you might want to upgrade to a 100 amp unit.
GM has a remanufactured 100 amp alternator, designated as a Model
12SI. It is available from your GM dealer and it is the exact same physical
size and configuration as the 63 amp model. It is a GM #10497082 or Delco
#321-269. Prior to the introduction of this model, all alternators of over
63 amp output, were physically larger and a different mounting configuration.
The 12 SI will bolt right in place of your 63 amp alternator.
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