BUT FIRST! Do you have a negative ground electrical system? If not, stop what you are doing, and back up to the page on negative to positive ground conversions. An alternator will not work with a positive ground system. Complete the ground conversion first then come back here!
Second, if you don't have a schematic of your Rover, get one now. Too many Rovers have lost wiring harnesses to backyard ingenuity with no documentation, and I wouldn't want to see your Rover become another casualty to the curse of Lucas! Note on a photocopy of the scematics any changes you make. This will make your life easier the next time Joe Lucas' ghost comes to visit your car.
The most difficult part of the process is the mechanical attachment of the alternator to the engine. You can use Land Rover alternator brackets. You may be able to find a bracket off another vehicle in a junkyard that can be adapted. If you can't find brackets, you do not need to give up, however, read on.......
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.
Next, you will need a Delco 10si alternator. One that fits a Land-Rover well is specified for a 1970 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. The double pulley gives you a bit to play with when alignment time comes. I understand an alternator out of a '75 Olds Delta 88 with air-conditioning will work as well, (air con gets the double pulley, I think). Click the shiny new alternator to learn just about everything you need to know to get the right alternator or to change the plug position of an alternator you already have.
FIRST, DISCONNECT THE BATTERY! This is not optional, you will have some fireworks if you do not.
Remove the old dynamo and associated bracketry.
The plug for the alternator circuit has two wires leaving it. One is a 10 gauge red, the other a 14 gauge white. The red one is the wire that sends juice to the battery. It also tells the alternator when the battery needs a boost. The ammeter is in this circuit as well.
The white wire is connected to the ignition switch. It excites the internal regulator, allowing the alternator to begin charging. It should be connected to switched, 12 volts. If it is hooked into an unswitched circuit, the alternator will feed power to the coil with the key off, keeping the engine running. The alternator warning light, if you have one, is in this circuit.
When the ignition switch is first turned on, the sense connection on the alternator is actually almost at ground potential, so the charge lamp has 12 volts on one side, ground on the other and lights up. The alternator is not self exciting, it requires a small amount of current flowing through this sense circuit to start charging. That's why if the white wire is not hooked to anything the alternator will never start to charge. After the alternator starts to charge, the white wire sense terminal goes to the same potential as the alternator output terminal. This means that since the charge lamp has the same voltage on both sides it goes out. Of course if you don't want (or have) a charge lamp you can just hook the white wire to switched 12 volts.
Hook up the 10 gauge red from the plug to the stud on the back of the alternator using a quality ring terminal. The red wire running to the ammeter attaches to this stud as well. Loosely install the nut with a star lock washer onto the stud. Insert the plug into the socket on the side of the alternator. I like to use zip ties on my harnesses, but you can use whatever you want to secure your wires.
Next, bolt the alternator onto the lower bracket or directly to the mounting dog, depending on your choice of mount. Leave this bolt loose for the moment, and pivot the alternator upwards. Take the upper attachment bracket, and bolt the slotted hole to the top of the alternator. Leave this bolt loose as well. Next, decide which water pump bolt will be best to attach the bracket to. Make your decision based on the need to pivot the alternator on the bottom bolt to tighten the belt. Take out the water pump bolt, and attach the bracket.
The Lucas alternator brackets as used on later Series IIA and Series III bolt can be used to mount the alternator to the lower block and water pump. If you use the Lucas pieces, however, you will need to drill out the hole that the alternator mounting bolt goes through. It is only 5/16" in diameter and the Delco unit needs to have a 3/8" bolt to fit properly. A bit of drill/file/Dremel work should do it. After drilling, bolt the lower bracket to the block. Alternatively, you can drill out the block mounting dog to the same 3/8" hole diameter and bolt the alternator directly to the block. That is what I do, as shown in the photo.
The pulley of the alternator must align with the water pump and crank pulleys. If it does not, use washers as spacers between the bracket and water pump to move it backward. The double groove pulley allows you to have an extended pulley to help align the belts. Play a bit, and try not to get frustrated. I use my eyeball as an alignment tool, but some folks use a straight edge as an alignment tool. Don't be fooled, the alternator shown here is a Ford alternator, but it shows the pulley alignment process.
My wiring harness is completely custom, so I am going to give the practical aspects of wiring at this point. If you have any doubt whatsoever about your ability to wire this correctly, find some assistance. Many streetrodders use this type of alternator, so they are a good resource.
The 10 gauge red wire should be on a direct path to the battery's positive terminal. It sends juice to the battery as well as monitoring it's state of charge. I ran mine to the ammeter, and another wire, (also 10 gauge red), from the other side of the ammeter to the battery side of the starter solenoid (I use a Ford starter solenoid). From there, the positive battery cable completes the circuit to the battery. There is no need to run the wire through the bulkhead except to hook up an ammeter. If you decide to go through the bulkhead, make sure to replace the grommets with new thick rubber ones. A fusible link in the circuit is also strongly suggested from a safety standpoint. I ended up putting in a 40 amp manual reset circuit breaker instead. I found one at a marine supply house. Remember, if this wire shorts to ground, it has the entire battery behind it. Things will spark and smoke.
Finally, take the red wire from the ammeter, and the red wire from the plug and connect them to the alternator output stud, and tighten down the nut. Connect the two white wires together. Use quality solderless connectors and shrink wrap.
A few thoughts here: if your ammeter reads backwards, reverse the wires going to it. Also, the Rover ammeter is rated for 30 amps. The 10si alternator puts out 63 amps. Needless to say, the ammeter will peg when you first start the vehicle. It should, however, settle back down in short order. I have to tap mine with a finger sometimes. If this disturbs you, install a more modern ammeter, or just run the 10 gauge red wire around to the starter solenoid, leaving the ammeter out of the circuit. Lastly, leave some slack in the wires between the alternator and the inner wing, to compensate for engine movement.
The white wire needs to be hooked up to a switched power source. I ran mine straight to the ignition switch (I use an Echlin tractor ignition switch). If you have an alternator warning light, it should be in this circuit. This wire excites the alternator's internal regulator. If you inadvertantly hook this wire up to an unswitched power source, the alternator will send juice to the coil with the key off, and you will not be able to turn off your engine.
You may or may not be able to use you old belt, depending on the length of your adjusting bracket. Put on a belt, pivot the alternator away from the engine to achieve proper tension, and tighten down the attaching bolts. Take another good look at your alignment with the belt on. If you are relying on your eyes, you may see the need to alter things slightly. If you like it, tighten the attaching hardware.
Next, turn the key to on, look for sparks, smell for smoke and feel the wires for heat. If all is well, crank up the engine, and check again. To test the output, hook a voltmeter between the battery terminals with the engine running. At 2000-2500 RPM the voltmeter should read between 14 and 14.5 for a charge situation. 12.5 indicates no charge, and above 15 means an overcharge caused by a bad voltage regulator. The Delco alternator doesn't start putting out juice until it is spun at greater than 1000 RPM
Make sure all your wire connections are tight, that the wires are neatly and safely ran, and that they are secure. Reconnect the battery, and check for 12 volts at the stud on the back of the alternator with a voltmeter. Look the wires over one more time.
Save them all! You can put away the old voltage regulator now, and along with the dynamo and bracketry, you have some valuable parts for someone who wants to restore their Rover to that level of authenticity. Auctioning them off on ebay may actually cover the costs of this swap for you!
From a mounting standpoint there is no difference between the three wire Delco, and the one wire Delco. The advantage of the three wire set-up, however, is that the alternator is able to adjust it's output for the voltage needs behind the dash, at the end of that white wire. A one wire alternator essentially has that white wire hooked back to itself, and cannot adjust for voltage drops in long wiring harnesses, lights being switched on, etc. The one wire alternator will keep your battery charged, but when running lights and accessories it cannot compare to the three wire version. Also, the three wire Delco is available virtually anywhere, and is far cheaper. The ONLY advantage of the one wire set-up is ease of installation. In the real world, the three wire alternator out performs it, and if you can hook up one wire correctly, you should be able to hook up three right! You can read more about this here.
Many thanks to Wayne Peeler ('64 SIIA 88")
for his clarification on the purpose of these wires!
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