Fred Dushin Ben Smith Dale Desprey Bill Maloney Bruce Fowler Dave Bobeck Dixon Kenner Alan Richer Mike Loidice
BBC Top 
Gear Land Rover vid 5mb Part of a series where people picked their 
favourite car for an 'all-time' greats poll. The Land Rover won hands 
  Vehicle Identification  
  History, Production, Sales 
  Repair & Maintenance
Data & Specifications
Chassis Numbers
Alternators & Generators
Installing an Alternator
Alternative Alternators
Body & Chassis
Perils Of Ownership
Forward Control
  Clubs & Parts Suppliers
What's New
  Contact Us
  Return to OVLR
  Return to Rover Web

Series Land Rovers

Alternate Alternators...

or GM'ing your Lucas Bits

Origional Author: Alan J. Richer (OVLR)

I've seen many a post asking the question "How do you get rid of this blasted Lucas generator?", so I've decided to pull together the random bits of information I have on the subject into a coherent format, presented here for your pleasure. Thanks to Bill Grouell for walking me through this on my own car when I did it, and helping me understand it so I can share it with you all.

DISCLAIMER: IF you're uncomfortable with electrical work or mechanical fitting, DON'T DO THIS WITHOUT HELP!
I'm not responsible if you get burned, zapped, bitten or otherwise damaged by your car. Now that that's over..... (and my lawyer has stopped shaking in his wingtips)....

The subject at hand is going to be switching your car from a Lucas dynamo to a GM internally-regulated alternator. These are inexpensive, one-package solution to the low output current problem of a 20-amp dynamo. This is done by removing the dynamo and its associated control box, jumpering the wires which were once connected at the junction box to allow 12 volts to get where it needs to, installing new wires to connect the GM alternator into the car's electrical system, modifying the mountings to accept the alternator, and mounting and connecting the new alternator into the system.

Note 1: This assumes that your car is already a negative-ground vehicle. if it isn't, you're going to need to worry about a lot more than this when rewiring, like swapping the battery around and dealing with the fuel gage and other things. Do the positive-to-negative conversion first, then do the alternator swap. One thing at a time makes things much easier - it's easier to figure out where you blew it.

NOTE 2: If you don't have a schematic of your car, DON'T TRY THIS. Too many Rovers have lost wiring harnesses to inexpert tinkering with no documentation, and I'd hate to see your car become another casualty. Schematics are cheap insurance - they can save you many hundreds of dollars of damage.

NOTE3: If you have schematics for your Rover (and you really should if you're going to do electrical work of any kind) MARK A PHOTOCOPY OF THE SCHEMATICS with the changes you make! This will make your life easier the next time Joe Lucas' ghost comes to visit your car.

1. Obtaining the needed bits, or hunting the wild current...

The only item you may have trouble running across for this installation is a Rover alternator bracket. If your car has such an item already mounted on it, you're all set. Else, you can modify the original mounts, or get a bracket from your favorite used-parts dealer or a derelict Rover. I was changing engines at the same time I did this, so my new engine already had the bracket. Personally, I recommend changing the bracket.

GM 1-wire alternators are easy to come by in the US and Canada. The specific one that fits a Land-Rover well is the one specified for a 1975 Chevrolet Nova, as it has the plug-in for current sense on the right side (when facing the pulley end), and is available with a double pulley. Get one with the double pulley, as it will save a lot of tedious metalwork constructing extension spacers for the Lucas alternator mount we will install. Typical price I ran across for these was about $60 American for a remanufactured unit with a lifetime guarantee.

We also should add the the 10SI alternator that you want has an AC Delco part number of 321-39. To get a list of cars that were fitted with it go to:
and enter 321-39. Then click on vehicle list. I've never seen a double pulley one BTW.

At the same time as you purchase your alternator, buy the plug that goes into the two-prong socket on the side. This will be used to make connections to the sense and alternator warning light leads. With this, you will also need about 8 feet of wire in 3 colors, red 10-gauge for the alternator output, red 16-gauge for the sense wire, and white 16-gauge for the alternator warning light. These are the standard colors for a GM installation, and I chose to stay with them.

You'll also need some lugs and slide-on connectors for the wiring ends, some wire ties, some shrink tubing of the proper sizes to cover soldered connections, and a few #8 brass nuts and bolts for connecting lug together where the old generator box is removed.

2. Site prep, or clearing the mounts for the new parts.

FIRST, DISCONNECT AND REMOVE THE BATTERY FROM THE CAR! This can save major embarrassment, not to mention smoke shows.... We.ll put it back in later, when we're ready to go.

This part is actually easy. What we're doing here is removing all of the old bits to make room for the new ones. Simply dismount and remove the dynamo from its brackets, and then remove the dynamo brackets themselves, leaving the area clear. What we'll end up doing is attaching a Land-Rover alternator bracket to the mounting points in this location, so all of the old bracketing has got to go.

The control box for the dynamo's got to go, too, but don't remove it now. This should be done when the alternator wiring is installed, so that the proper connections can be made to the wires removed from the control box.

3: Building the new alternator harness

We need to build a small wiring harness with 3 wires:
  • 10-gauge red wire for the current output
  • 16-gauge red wire for the sense input
  • 16-gauge white wire for the warning light
To do this, take your alternator and set it on a work surface. If you're doing this on the kitchen table, cover it with something so the SO doesn't kill you. Looking at the alternator from the rear, you'll see a stud on the back with a nut on it, and a socket on the left side with two prongs. These are where the wires need to get connected.

Take the plug you purchased when you bought your alternator, and solder the ends of the red and white 16-ga. wires to it. The wires on the plug will be of the same colors, so match them up. Insulate the soldered connections with shrink tubing. Take the 10-ga. red wire, and attach a ring lug to it, soldering the connection and insulating the bottom of the lug with shrink tubing. This is going to be the current output lead.

NOTE: Don't buy el-cheapo ring lugs for this connection. They'll fatigue and break. Go to an electrical-supply house and get a heavy copper lug, or make one from flattened copper tubing of the proper diameter to take the wire end. You'll thank me on this one.

Put the ring lug onto the stud on the back of the alternator and put the nut on over it, just to locate its placement. Insert the plug into the socket on the side of the alternator. Now. bring the wires together leaving plenty of slack and harness them together with the wire ties about every 6 inches or so. stopping about 6 feet up. Leave the last 2 feet un harnessed, as these wires need to go to different places.

4. Wiring in the new harness

Remove the harness from the alternator, and starting at the alternator position, route the wiring across the front of the engine and down the distributor side of the block and up the firewall to the neighborhood of the fuse box. Use wire ties to secure the harness as needed, being careful to avoid sharp bends or contact with metal edges.

Now, trim the small red wire to reach the fuse box with slack to spare and solder/crimp on a quick-connect lug to fit the fuse box. On a Series IIa, attach the lead to the bottom fuse (unswitched power). This will allow the alternator to sense voltage drop in the system and correct its output as needed.

The other two leads need to go through the grommet the harness goes through into the dashboard. Drop the dashboard and locate the wires connected to the ammeter and the dynamo warning light. The output of the dynamo control box ran directly to one side of the ammeter, in my schematics typically on a brown-and-white wire. By following the schematics, you can tell which one for sure on your car. Unplug that wire and insulate AND MARK it, then strip the alternator output lead, put a large slide-on wire connector on it and connect it where the dynamo output lead was removed.

The dynamo warning light has 2 wires running to it. One is grounded along with all the other warning lights (typically a white wire), and the other ran to the dynamo control box (usually yellow). Disconnect the wire going to the dynamo control box, unsolder the bullet connector on the end, insulate AND MARK the old wire, trim the white wire going to the alternator and solder the bullet connector to it. Plug this new warning lead into the connector on the warning lamp.

Use wire ties to secure the wiring in place. Keep it neat, and future owners of your vehicle will thank you for it. We're not trying to create a SPOT here - use common sense and trim things up properly both under the bonnet and in the dash.

    The ammeter on your panel is only going to read to 30 amps. With the new alternator in place, it will ofttimes be pinned at the top of its range. If this disturbs you, I recommend jumpering the ammeter. It's not really suited to the new charging system anyway, and there is a not-so-small risk that the ammeter can be damaged by this behavior.
That said, I've disconnected mine - pinned gauges make engineers nervous.

5. Installing the new alternator on the engine

This is a multi-step process. First, we have to make the alternator and bracket fit together, then we need to mount the bracket, then the alternator, and belt the beast to the pulleys.

The Lucas alternator bracket as used on later Series IIa and III bolts on in place of the old dynamo bracketing. Before this, though, we need to drill out the holes that the alternator mounting bolt goes through, as it's only 5/16" in diameter and the GM alternator needs to have a 3/8" bolt to fit properly. An electric drill and a bit of care can accomplish this handily.

Now, mount the bracket to the engine. You will see, on the side of the engine where the dynamo was, two tapped holes side-by-side and a through-bolt hole below the first two. This is where the bracket goes on. Bolt on the bracket, with 2 5/16" washers under each mounting pad. We want to move the bracket forward a bit so the alternator lines up properly with the engine pulleys.

Now, I'm going to give you a choice.

The alternator can be bolted on as-is, using a longer belt. Personally, I didn't do this, as I found that it gets in the way, sticking out too far toward the wing.

What I did was to notch the web of the bottom bolt hole (the long one). The way it is made, there is a fillet of metal on both sides of this long bolt hole for support. I trimmed away the one that would be toward the engine, to give clearance for the alternator bracket. If you do this, you can use a standard belt, and the installation just looks cleaner.

Your choice.

In any case, use a 3/8" bolt with lock washer to mount the alternator to the bracket. Place 2 3/8" washers behind the alternator at the back of the mounting to soak up the extra space between the support arms and the alternator lower mount.

The upper support which once tensioned the dynamo needs to be moved as well, due to the larger diameter of the alternator. The best place I found for it was on the bottom-right water inlet bolt (of the three bolts in a triangle pattern on the front cover). Remove the bolt and put the hole in the bracket over it, with a spacer under it to get the bracket up out of the cover recess. Don't tighten the bolt until you engage and tighten the belt, as the bracket will shift up and down depending on where the alternator attaches to it.

6. Disconnecting and jumpering the old dynamo control box:

There are connections on the old control box that need to be jumpered, else the current's not going to go where you want. There are two different control boxes used on early Series vehicles, a 3-wire and a 5-wire, and I'll detail the changes needed for both here.

What you need to do here is leave the original wiring intact, and reroute the +12 volts around the connections once made by the control box. Typically, the only one you need to worry about is the connection between the fusebox and the ignition switch, and the wiring to + 12 for the accessory lead plugs.

On the 3-wire box (typically early + ground Diesel installations)

No modifications needed. Disconnect and insulate the terminals and wire-tie them to the harness neatly.

5-wire dynamo control box in a 2.25L Petrol negative earth installation, as well as 2.25 and 2.6 L IIB Forward Control:

Remove the two leads from lug A1 and tie together, then insulate. Remove and tie together the two leads from A and insulate. The F, D, and E leads can be insulated and tied down, as they are disconnected.

5-wire dynamo control box in a 6-cyl Petrol negative earth installation, as well as later negative-earth Diesel:

The two brown wires on the B terminals need to be tied together and insulated. The F, W/L, D and E can be insulated and tied down separately as they are disconnected.

NOTE: Make sure you verify this to be correct on your car. Ofttimes, wiring got shuffled about on these cars with little care for the schematics. Please be careful, and make sure you don't get victimized by some previous owner.

6A. What do I do with the old control box?

In writing this document of my reader/editors pointed out that many of these old bits are expensive to come by. At his behest (Hello, Dixon!) I am adding the part numbers and prices at the time of publication (1996).

Don't toss the bits out - someone trying for an authentic restoration will bless you for them!

Who ran with what:

Rover Engine Dynamo
Series I 1,595cc petrol Lucas RF96/2 (early)
Lucas RF95 (later)
Series I 1,997cc petrol Lucas RF96/2 (early)
Lucas RF95 (later)
Series I 2,052cc petrol Lucas RF96/2 (early)
Lucas RF95 (later)
Series II 2,286cc petrol Lucas RB1106/37182
Series II 2,052cc diesel Lucas RB310/37189
RB310/37297 (later)
Series IIA 2,286cc petrol Lucas RB106/37290
Series IIA 2,286cc diesel Lucas RB310/37472 (to suffix C)
Lucas RB340/37517 (from suffix D)
Series IIA 2,625cc petrol Lucas RB340/37517

They want WHAT for one of these? (Spring 1996 prices)

Part Price (UKP) Notes
RF95 135
RB106/37182 20 screw fittings
RB106/37290 20 spade fittings
RB310/37189 110 screw fittings
RB310/37304 110 Lucas fittings
RB340 16

Know what you have. You don't want to throw the wrong one out. You can resell it to someone that needs it...

7. Final checkout and testing:

Okay, we're in to the home stretch now. With a belt in place, hand-crank over your Rover to make sure the alternator is set up properly and isn't going to jump the belt when you fire up.

Before reconnecting the battery, retrace all of your connections to ensure you've gotten it wired right. A little caution here can save an expensive smoke show.

Reconnect the battery and turn on the key. All of the warning lights including the dynamo warning light should come on to normal brilliance. If you have a meter, check to see that you have + 12 volts running to the large lug on the back of the alternator and the red wire on the small plug.

With this correct, start the vehicle. Odds are, the dynamo warning light will still be on. Don't panic, it's supposed to do that. Rev the engine and the light should go out. GM alternators do not start to charge until they get over 1000 RPM or so on start-up.

If the light went out, you're all set. Inspect the mountings of the alternator to make sure all's well, and check the wiring for possible trouble spots rubbing on brackets and so forth. If you want to, check the voltage at the battery terminals. With the alternator charging, it should be 13.5 volts or higher.

If the light didn't go out, or if it never went on, recheck your wiring, especially the heavy lead going to the alternator and the small red sense lead. If either of these is disconnected, the alternator won't function properly. Also, as above, check the voltage at the battery to see if the alternator is actually charging.

8: Conclusion:

This modification , while a simple one, lets you update your Rover to the current output needed for more modern amenities like a stereo, driving lights and so forth. This way, on those dark nights with wipers, lights and heater fan going, you can drive without depleting your battery.

Good luck, and happy alternating!

Copyright Dixon Kenner, 1995-2011. Last modified March 11, 2009.
Comments? Send mail to Dixon Kenner or Benjamin Smith
Site Designed and Created by Bill Maloney
Russ Wison
Russ Dushin
Tom Tollefson
Steve Denis
Don Watson
Fixing It
Ted Rose's Buns
Andy Grafton