Fitting an alternator

I decided to convert the alternator electrics because I wished to have a practical car for modern driving rather than an exact replica. I also did I in preparation for a 3000 + mile drive to ltaly. I figured in case of difficulties a Lucas alternator stood more chance of getting fixed an the continent than a dynamo. The conversion brings two main benefits: first, the alternator's greater output which enables it to cope with lights, wipers, heater blower etc. all together without draining the battery; secondly, most electrical accessories these days assume negative earth and, of course, reversing the polarity of the car is implicit in the conversion. The parts needed are: a suitable alternator with front bracket (see below), connector plug and wiring to fit, original style bullet connectors, long reach rear mounting bracket, a modification to re-mount the coil (custom made or use part from another car), new petrol pump or replacement parts to convert (see below), possible new main battery connection leads if reversing the battery in it's box changes the length required, small supply of wire of suitable load rating to match existing. I got the major parts from a scrap yard. The alternator and wiring was from an 1800 Marina and the long bracket from a Mini. The best type of alternator is Lucas ACR with three terminals, two large and one small. lf you find one in a car, take the front bracket and wiring with it. This may mean cutting carefully into the harness. The replacement rear bracket is because the alternator is shorter than the dynamo. Luckily BL had to cope with this before they changed engine castings and part, 12G1053, is still listed. The coil can be mounted on the alternator by fabricating a large diameter strap on the inner wing. A long ignition lead will probably be needed. Once the alternator is fitted, check that you can tension your fan belt properly or get a shorter one. The ACR alternator uses an integral regulator and the Magnette regulator is not needed. lt can be left in place for looks. I decided not to use any of the dynamo wiring, though this is possible. With my method all the wires are detached from the regulator. For neatness with existing connections I used bullets rather than modern alternatives. The regulator wiring is as follows: Terminal Modification A & A1 Connect all A wires (brown) together. D Blank oft at regulator and dynamo end (not used). F (Two wires) Check which is the dynamo field coil connection and blank off with the D wire at both ends. The other wire is the ignition light feed and is connected to the smaller of the three alternator wires. E This wire merely earthed off the old regulator but is also used to earth nearby equipment, so any black wires should be connected to the one leading to the body earth point. The two larger wires on the alternator wiring come together on the alternator end in a large round connector which should be suitable to connect straight to the starter solenoid on the same side as the battery main feed. lf not, a suitable main connector will be needed. Remember, the battery will be connected in reverse polarity so this side of the solenoid will now be the positive. lt is not polarity sensitive so the wires can be left where they are and the alternator connection made an top. Only the battery end at the main (thick) supply wire needs changing from the negative to the positive battery terminal. Similarly the earth strap will be connected to the negative side. Do no re-connect the battery until all jobs are done. The petrol pump is polarity sensitive so the answer is to fit a new pump (part number AZX 1331). However, if the latest type of pump is fitted, (AZX 1332), it is possible to fit a negative earth connector (CZX 1005). Fit new points too! Lastly the clock is polarity sensitive. Since very few of them work it is not a major problem! However, if you want it functional get an instrument specialist to convert it. Otherwise disconnect it and leave the lead with a connector to insulate it. When conversion is done the ampmeter will behave differently, showing the amount of power flowing through the system, not the degree of charge/discharge to the battery. lt will also register backwards unless you reverse the terminals. You need to get used to it showing a heavy discharge when a lot of equipment is in use. For normal daylight dry driving it will read slightly off the middle and will show slight deflections for fuel pump pulses and indicator flashes. Before switching on and starting up, check all connections carefully. Ask an assistant to work in the car while you observe the engine bay for signs of sparks or hot wires. The finished job looks neat, a few extra connectors where the regulator used to be. My experience is that the benefits are well worth the loss of originality, and it is all easily reversible anyway.

Malcom Eades