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MG MGA - Alternator conv. problem

Ok
I picked up a Lucas alternator to do a conv. on my 1600. Got it all put together as per Bob Munchausen's instructions.
Problem 1
The ignition warning light doesn't come on with the key but it is getting 12v. to the socket. Bulb is fine.
Problem 2
I am getting 12.5v output @ 1500rpm from the alternator. Shouldn't it be higher??
Thanks for any imput
Kris
Kris Sorensen

The output should be in the range of 14.7 volts. I suspect it is time to go back into the alternator and recheck everything. Are you certain that the brushes were released after installing. If I remember correctly there is a small hole in the end to insert a small wire ( paper clip straightened ) to hold the brushes while installing the end plate.Then pull out the wire and the springs will put pressure on the brushes to contack the slip rings.
Sandy Sanders
conrad sanders

Kris,

It appears that there is something wrong in the way it is connected.
For an ignition light when using an alternator, with the engine stopped, the current from the battery goes to the the bulb and then through the alternator and then the circuit is completed. The alternator when it starts up builds up to 12 Volts where it balances the battery voltage and the light goes out. This is nothing like the setup on a generator.
If your light does not come on with the engine stopped, but the bulb has 12 Volts at the socket, the circuit through the alternator is not complete.
With your 12.5 Volts it appears that the alternator is not working. If you allow for a + 0.5 Volt error on your meter, you may be just measuring battery voltage. Otherwise your alternator has a serious charging problem.
One reminder. Do not run the alternator with the battery out of the circuit as this normally blows a diode in the alternator.

Mick
Mick Anderson

The problem is in the indicator light circuit. The alternator will not work without the voltage throught the indicator bulb getting to it. I would suspect that the wire from the indicator to the alternator is connected to the wrong place or the diodes or regulator in the alternator are bad. A good auto electric shop (NOT Auto Zone, Shucks, Checker or any of those places) can test the alternator for you and tell you what it needs (and probably supply the parts. Good luck - Dave
David DuBois

Looks like the problem is solved. I was searching around finding other alternator conversions when I came across Barney Gaylord's site. I rewired the car using his example of using the existing voltage reg. as a terminal block. All seems fine now. Don't really know why it didn't work before but I guess that's just the way it goes. Thanks all for your imput.
Kris
ps Thanks to Bob Muenchausen for getting back to me.
Kris Sorensen

Kris, et al:
I have decided to remove my webpage on an MGA alternator conversion (Bosch Type) permanently. After reading Barney Gaylord's comments, I simply decided that the info on my site was too old now and not nearly as good as what he or Moss have to offer.

And besides, if you can now get an outta-the-box alternator conversion from Moss, why bother with all of my site's monkey business?? Ford Fiesta Alternators were a confusing choice and never that easy to come by anyway, and now that there are better alternatives out there, why not make use of them??

For most owners contemplating such a conversion, it is good that Moss finally discovered the value of offering such a conversion and the pieces that go with them.
Bob Muenchausen

This thread was discussed between 10/01/2005 and 12/01/2005

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This thread is from the archive. The Live MG MGA BBS is active now.