Download This procedure covers going from an external regulator to an

ALTERNATOR UPGRADES FOR 240Z – 280ZX
This procedure covers going from an external regulator Nissan alternator to a GM
CS alternator. Finally, I recommend using a CS130 alternator. This is a collection
of procedures from different sources combined into one complete procedure.
Nissan External to Nissan Internal Alternator Swap (Putting an
GM CS130 alternator in a '77 or earlier 280Z or a ‘70 –‘73 240Z)
Why Swap?

The original '77 280z's build has an external mechanical voltage regulator that is
unreliable and unstable with age. It is actually based upon elements that open and
close many times each second due to heating and cooling. The principal is
not much different than the overheat protection devices commonly used in your
toaster and hairdryer. It also requires frequent adjustments of gaps much like
spark plugs. The newer GM CS130 alternator incorporates a built in solid-state
voltage regulator that requires no maintenance and is more stable.

The wiring between the alternator and voltage regulator typically is problematic.

The Z alternator is rated at 50A. The GM CS130 alternator is rated at 85 amps at
idle and can be upgrade to 105 amps at idle.

The upgrade is pretty much bolt and go. Two wires need to be jumpered or
spliced and that is it!

The CS130 unit is newer, readily available at all parts stores, and is inexpensive.

The CS130 unit is rock solid and the DC voltage is 14.4V at all RPMS (as
measured on mine).

The Voltage gauge and hunting of the fuel pump will no longer waver.
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
Disconnect - Negative battery terminal (Note - I repositioned my battery so that the
negative terminal is near the fender).
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
Here is a pic of the stock 77 alternator before doing anything (You can use it as a
reference if needed.)
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
Here is a another reference pic
FYI Name plate on a stock 1977 alternator "12V @ 50A"
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
Disconnect the cables to the alternator
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
Remove the three bolts that hold alternator in place. I used a 13mm socket for the top
bolt that clamps it to the bracket and a 12mm socket for the two bolts holding it to the
engine block.
Here is a picture of an easy way to access the lower front bolt. The rest of the work can
be done from the top.
Unclamping the carbon canister and moving it aside takes 30sec to do and helps a lot.
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
Alternator removed
Freshen contacts/connectors on the cable ends with sandpaper or scotch pad and contact
cleaner (Caig Deoxit above). You only need to do the BAT, “E” and “T” contacts.
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
Question: I would like to know if anyone has converted from the external regulated
alternator to an internal. What wiring did you change?
Answer: First, a little background: The 60 amp internal regulator alternator was used on
the '78 280Z and then the non-turbo 280ZX. I have also seen it on the '78-'85
810/Maxima and the '81-'85 720 pickup trucks. It is marked "LR160" on the case. There
was also a 70-amp version (marked LR170) that was used on the 280ZX turbo cars.
[Note: It looks like the '84-'86 non-turbo 300ZX 70 amp alternator could be used as well,
but the wiring connectors are different, so get (i.e., cut it off) the corresponding engine
harness connectors as well if you get one of these alternators. I will write this up this
conversion later.]
Because I do not like to give instructions without some explanation of what you are doing
(it makes troubleshooting easier), I will start by describing the internally regulated
alternator's electrical connections:
1. An "L" connection, which goes to a "switched" 12V supply. By this, I mean a
12V source that is active only when the ignition switch is in the ON position. I
use the mnemonic "L" for "lamp", the alternator-warning lamp (if used) is in
series with this connection. This terminal also supplies the "excitation" current to
the alternator field winding at engine turn on, allowing the alternator to begin
producing voltage as the engine is ramping up to idle speed. Once the alternator
rotor is turning fast enough, it generates its own supply for the field winding and
the current in the "L" connection stops flowing. The warning lamp (if used) goes
out.
2. An "S" connection, which goes as close to the positive terminal of the battery
as physically possible. The "S" connection "senses" the battery voltage and this is
the voltage that the regulator is trying to control. This connection has high
impedance, so it only draws only micro amps from the battery, so it can be left
connected without fear of battery discharging.
The "L" and "S" connections are in the plug connector on the rear
of the alternator that looks like the capital letter "T". The top
of the "T" is the "S", and the other part of the "T" is the "L". Or in crude ASCII
art:
............
: -------: "S"
:.... | ....:
:|:
: | : "L"
:...:
3. An "A" terminal, which is the output of the alternator, which also is connected to the
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
positive terminal of the battery. This connector carries the charging current. Because of
the high currents this wire must carry, it is a low gauge wire, which means it has a large
cross sectional area. For safety reasons, a fusible link should be in series with this
connector. The "A" terminal is the insulated threaded stud on the rear of the alternator.
Of course, someone may ask; "Why do you need two separate (the "S" and the "A")
connections between the battery and alternator?” It is because of the fact that even large
wires have some resistance, and therefore there will be a voltage drop between the
alternator and the battery when the battery is being charged. If the regulator sensed the
alternator output (which is higher in voltage) and not the battery terminal, the result
would be undercharging of the battery. Now there are alternators, which work this way,
but they need a large diameter charging wire to reduce the voltage drop. The separate "S"
connection is a much better method of regulation.
4. Finally, there is a ground connection on the alternator, although the case is a good
ground connection to the engine block.
Now, the following procedure only applies to the 240Z. The 260Z has electrical
connections between the regulator and the interlock module and the electric fuel pump, so
it is more difficult to convert to an internally regulated alternator, but I have a procedure
for it as well.
1. Disconnect the battery.
2. Unplug the external regulator and note the color code of the wires that are on the
regulator connector of the engine wiring harness. You will be connecting some of these
wires together, so get another plug from a junked regulator or cut the one off your old
regulator. Now the wire colors I will be referring to are on the regulator connector of the
engine wiring harness. This is because although the regulator wire colors match the
engine harness with the stock regulator, I have noticed that some aftermarket regulators
have a different wire color code.
3. Connect the white wire to the yellow wire. This connects the battery to the "S" input.
4. Connect the black with a white stripe wire to the white with black stripe wire. This
connects the "L" terminal to a switched 12V.
5. Disconnect and unbolt your old alternator. Bolt up the new alternator. Depending on
what particular internally regulated alternator you use (I have seen different pulley sizes),
you might need a different length belt.
6. At the alternator, connect the white with red stripe wire of the engine wiring harness to
the threaded stud (the "A" terminal) on the alternator. This connection provides the
charging current for the battery. Connect the black ground wire to the alternator. Do not
forget to include any bypass, or filter capacitor. Plug the two-pin "T" connector into the
alternator.
7. Re-connect the battery and start the engine. With a good digital voltmeter measure the
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
voltage directly across the battery terminals. This is the charging voltage. It should be
14.7V +/- 0.3V, but this voltage is a function of the ambient temperature and the state of
charge of the battery. If the voltage reading is not correct, then re-check your wiring.
More than 15.0V indicates that the "S" connection may not be connected correctly.
Converting from a NISSAN External to GM SI Alternator
BTW, with regard to the terminal marks on the GM alternator case:
GM/Delco "1" = GM/Delco "R" = Datsun "L" = warning lamp/Switched +12v
GM/Delco "2" = GM/Delco "F" = Datsun "S" = constant +12v current sensor
I had originally tagged this onto another thread but have completely rewritten it with
updated information, hence the new thread...
There are other posts on doing the Delco Remy (GM) alternator swap on an L6 engine,
but I thought someone might want to see some pictures of what we did on all three of our
280Z's.
Other alternator swaps have their advantages and this particular swap is not for everyone.
My reasons for going with the Delco alternator were:
1. The exact Hitachi replacements for the 1976 280z or the 1978 280z's were not in
stock.
2. The old external voltage regulator could be eliminated on the '76 Z.
3. A GM alternator can be had anywhere, anytime for a low cost. It makes one less
thing to worry about on a long trip.
4. It was fairly easy to do with the tools I have.
5. On two of our Z's, the bolts holes at the front of the mount were stripped and the
bolts were missing. The swap solved that problem as well.
Click here for a great website with info about the Delco Remy 10si/12si alternators.
There are three methods of mounting the Delco CS130 alternator that I am aware of:
1. Mount the alternator upside down. The place on the alternator where the
adjustment bolt normally goes will bolt right up to the existing mount with no
modification. The trouble is that some people have said that the thin metal on the
alternator eventually bends.
2. Buy or fabricate a new alternator bracket. The mounts I have seen advertised
were $80 to just over $100.
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
3. Modify the existing bracket. This allows the alternator to mount to the engine
much as it does in GM cars.
We went with option #3 since it seems to be reliable, inexpensive, and easy to do.
Here are some of the tools used:



Reciprocating saw or hack saw
Bench grinder
Drill bits from 1/4" to 13/32"
Parts used:






M10x113 bolt (HELP! Part #45636)
M10-1.5 hex head flange nut (Dorman 982-010)
M10 spring washer
M10 flat washer
5/16"-20 bolt for ground strap
GM CS130 alternator plug
Basic procedure:
1.
2.
3.
4.
5.
Remove Hitachi alternator and alternator mount.
Shorten mount and drill a through-hole.
Move the v-hub from the original alternator to the GM alternator.
Install the modified mount and GM alternator.
Change Field / Sense plug and put on larger ring-terminals.
This is the third time I have done the swap. It takes between 2 and 3 hours to do the job
if the parts and tools are all lined out.
A picture of the new AC Delco alternator with modified mount next to the old Hitachi
alternator with original mount:
A picture of bolt and flanged nut:
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
First, we removed the alternator-mounting bracket from the side of the engine and cut
about an inch off the front mounting surface. We didn't want to accidentally cut too
much off so I left the bracket a little long and then mounted it to see how much more
needed to be cut off. I started by cutting off 1.25" (For CS130 cut 1.375” off). This
placed the alternator pulley too far to the front. I used a bench grinder to do the fine
adjusting. To get the alternator pulley was in perfect alignment, the bracket had to be
ground so that it was exactly 1.7" deep (For CS130 trim to 1.625” deep).
Next, the rear bolt hole needs to be enlarged and extended through the front of the
bracket. The M8 threaded bolt hole needs to be enlarged to accept an M10 bolt. We used
a 1/4" drill bit inserted into the rear bolt hole and drilled through the front. I worked up
to larger drill bits and drilled the entire bolt hole until it was 13/32", which is just big
enough for the knurled shaft of the M10 bolt. Actually, my drill set did not include a
13/32" drill bit, so I worked up to a 25/64" bit and hogged the hole out to make it large
enough for the M10 bolt. For me, drilling the mount was the hardest part of this little
project. It is a difficult process to keep the drill bit from grabbing while drilling without a
drill press. Still, it only took about 20 minutes to get the mount modified.
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
Here is the modified bracket mounted to the engine:
Converting from GM SI to a GM CS144 or CS130 Alternator
Additionally, the upper mounting tab of the CS130 is already threaded to accept an
M10x1.5 bolt. This will may require modifying the stock alternator bracket to allow for
an M10 bolt.
All you have to do here is trim the mounting bracket the addition 1/8” to account for the
thicker flange on the alternator. This makes the bracket length approximately 1.625”
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
long. This will allow you to use any replacement alternator without modifying the case.
The CS130 alternator tab is 3/4”
thick.
CS130 tab - 3/4-in. thick. The black mark shows the difference.
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
Next, you will need to switch out the serpentine pulley for the L28 v-groove pulley.
Note: On the other hand, you can purchase a small v-grove pulley from Quality
Power. The smaller pulley will allow higher output at idle. They also have higher
output alternators which can put out up to 105 amps at idle.
http://www.qualitypowerauto.com/
Finally, you will have to modify the stock alternator bracket. The slot may need to be
widened as mentioned above to fit an M10 bolt, but it also may need to be lengthened a
bit to allow for a slightly longer belt. You may not be able to use the stock belt as it may
be too short or too long and the alternator housing will not clear. I bought belts one size
smaller and one size larger and returned the ones that were not needed.
Note: With the pulley I had, I used a stock air conditioning belt for the alternator.
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
Wiring changes for using a CS130
Using the CS130 will reduce the modifications to the mounting of the alternator. A stock
CS130 alternator will produce about 80amps at idle and a performance mode will
produce about 100 amps at idle. Max output is approximately 100 amps for regular and
130 for the performance version. The mounting bracket will need to be shortened.
This is the model of CS130 alternator that you will need to use in a Z. The ears are
exactly opposite of each other.
Now it is time to discuss the electrical modifications at the alternator. Never fear, these
are easy. To make it stupid simple, go to an auto parts store and get a CS130 wiring
harness. An electrical connector is made to convert stock alternator harnesses to CS
alternators. It has two connectors, one on either end. The yellow wire is the exciter and
the large is the battery sense. Simply, cut off the connector that does not attach to the
alternator, attach male spade connectors to your wires to the new sub harness, and plug
them in to the “T” connector and you are done!
S-connect this right to the battery output "+" on the Alt. with a ring terminal
F-Not needed
L-Connect to 12V switched source
P-Not used
L = GM/Delco "1" = GM/Delco "R" = Datsun "L" = warning lamp/Switched +12v
S = GM/Delco "2" = GM/Delco "F" = Datsun "S" = constant +12v current sensor
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
............
: ------- : "S"
:.... | ....:
:|:
: | : "L"
:...:
I also recommend that you take 10 gauge or larger wire and ground the alternator to the
engine block. I also recommend taking a ground wire from the battery to the engine
block. I used 4 gauge battery cables to ground the battery to the body and the battery to
the motor. This will improve the electrical performance of your car.
I have noticed that I now charge around 14.25 to 14.5 volts at idle, a significant jump for
me. The car idles smoother and it seems to rev better.
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
Locate Voltage Regulator. It is under the bracket holding the fusible links. A 10mm
socket removed the four bolts.
Here is the bracket removed. You can see the Voltage Regulator and its inline connector
Here is a schematic of the ZX alternator. Note the internal voltage regulator.



BAT (+12V battery) connection (White with red striped)
E (earth/ground) connection (Black) is the same on both alternators and requires
no changes.
S (Sense) connection (Yellow) gets connected to a +12V
source
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ALTERNATOR UPGRADES FOR 240Z – 280ZX

L (Lamp) connection (White with black stripe) is connected to a +12source that is
active only when the car is cranked by the starter. (You can see the node in the
schematic where the L lines get power from the warning lamp when cranking and
then from the alternator windings via the 3 clustered diodes when operating.)
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
Electrical Jumpers
NOTE: My recommendation is to cut the connector off the voltage regulator by
cutting the wires as near to the regulator as possible. This will allow you to make
the changes to the voltage regulator wires and not to the harness of the car. This
will allow you to change back if you wanted to return your car to the stock
configuration.
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
This is the wiring to the electrical harness connector (as seen on the car when you unplug,
remove, smash into bits, tramp on, and throw away the external voltage regulator)
Here are the two connections to make - 2 to 3 and 1 to 5.
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
Connect, solder, heat shrink, insulate and wrap
Double check everything (wires correct and snug, bolts tight, fan belt snug and on correct
pulleys, no tools in engine compartment, carbon canister put back and hose put on,
correct jumpers at connector)
Connect -neg battery cable briefly (1sec) and make sure there are no sparks or smoke!
If all seems ok, connect -neg battery cable and try starting. Watch for smoke and watch
the battery gauge for correct voltage and Red LED functioning.
Enjoy!
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
FYI if you have a '76 280z, the colors are slightly different:


The white with red striped wire on the 77 is just white on the 76 (still pin 2)
The blue wire on the 77 is green on the 76 (still pin 6 and unused)
Here are the '76 connections for your convenience
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
Ok, many people m still confused by what is being done to the wiring. Here are the
jumper connection details for each year
1975
Connect 1-5
(lamp to
green & red to white & black
windings
common)
Connect 2-3
white to yellow
(+12V to Sense)
Note: Some 1974/5 cars only
have 5 wires and will need to
get switched +12Vdc from
another source for the “L” wire
on the alternator. We used
+12Vdc from the test plug
located near the coil/headlight.
1976
1977
blue to white & black
blue to white & black
white to yellow
white & red to yellow
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
Changes Specific to a 240Z
'73 240z Connector to VReg (Rectangular)
I followed the instructions I found on the net and it worked perfect. Also, before you do
this, do a search on this site for diode. Sometimes when you convert to an internal
regulator, the car will not shutoff when you turn the key to off, this is due to current
bleeding through the alternator, a diode must be placed in the circuit to block it
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ALTERNATOR UPGRADES FOR 240Z – 280ZX
Good luck Converting to an internal regulator alternator
Note: You can use the following 240Z wiring upgrade from MSA if you do not want to
set up the connector yourself.
Alternator Upgrade Adaptor, 70-73 240Z
Quantity in Basket: none
Code: 12-4067
Price:$19.95
12-4067
Quantity:
LNP1
1
Add To Basket
Description: The Datsun 240Z was originally equipped with a 40-amp alternator, and a
mechanical, points-type external voltage regulator. Today, many, if not most 240Z's
have various electrical-dependant upgrades, like electronic ignition, halogen headlights,
larger stereos, cd changers, DVD players, GPS systems, and more. The crude mechanical
voltage regulator is unable to deliver a stable reliable output. That is where this Adapter
Kit comes in. It is small, weather-resistant, and simply plugs into the wiring harness in
place of the original voltage regulator. The diode is pre-installed and self-contained.
Bolt on the ZX alternator, plug this adapter in, and you are done! Additionally, since no
wiring on the car is actually changed, this upgrade is fully reversible. So if you ever
needed to move the Kit from one 240Z to another, the original configuration can be
restored in minutes. Then the kit can be transferred by reversing the instructions. You
will need to source your own internally regulated alternator. You can also simply see
related items below for our complete kit including an upgraded, quality remanufactured
Bosch Alternator, for one special combined price with no alternator exchange needed!
Model Guide: Datsun 240Z
Code Guide: Datsun S30
Year Guide: 1970, 1971, 1972, 1973
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