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MG MGA - MGA Generator

Anybody know the amperage of the MGA Generator? I was thinking of putting an MGB generator on my MGA assuming that it will handle more accessories. I believe they are physically the same. Any other thoughts would also help.
J Butler

They are a straight across swap, but I am not sure that the output of the early MGB generators is any higher than that of the generator used in the MGA (they may well be the same exact generator). Have you checked the MGA Guru web site at: My bet is that you will find the information there. Cheers - Dave
David DuBois

AFAIK the only difference is that the B unit has Lucar connections for the wiring instead of screw posts. I can confirm that the B unit has exactly the same dimensions.

dominic clancy

I cannot imagine what accessories you would possibly need to run that the generator could not keep up. If you got to have that much *rap take the good car. You'll be missing the pure driving experience of the A ;)
gary starr

They are basically the same unit. No advantage to swapping one for the other.
Steve Simmons

If you want more output you should fit an alternator, it will pump out up to 40amps which is almost double the output of a generator.

It is a really simple conversion and when I fitted mine it took me about an hour and it works brilliantly. I do lots of short runs in my car and I found that the generator just didnt re-charge the battery sufficiently.
For the purist, the alternator can easily be removed and the generator re-fitted.

Also, you dont need any extra special electrical or mechanical skills to fit the alternator.

Have a look at MGA Guru for instructions but make sure you read all of the article before you start as there are some important points to take in especially if you use the original voltage regulator box as a means of connecting the alternator.

Colyn Firth

Early generator was 19 amps, later changed to a 22 amp model. In later production the terminal posts changed from screw posts to push-on connectors, but still 22 amps. MGB generators are also 22 amps with push-on connectors. Mose replacement generators will be MGB type with push-on connectors, physically interchangeable except for the wire terminals (which are easily changed). There are a couple different pulley sizes, and belt length changes accordingly (and will also be different for an alternator).

For decades I had no problem with the generator, but repeated fault control boxes drove me nuts. I finally changed to alternator just to get away from the junky aftermarket control boxes. Aside from higher charging capacity, the alternator puts out higher voltage at idle or near idle speed, so you have bright headlights and battery charging when it's idling. Much better for short trips and frequent starting.

The small Lucas alternator commonly retrofit for these cars is about 42 amps (and easiest to install). It is hard to find a smaller alternator, and the small ones used for racing are expensive specialty parts. Larger alternators are all over eBay for dirt cheap, but occupy more space in the engine bay.
Barney Gaylord


If you can live with 22 amps, try swapping your electro-mechanical regulator for an electronic version. The swap largely solves the fluctuations and failures of the original style regulators. Also keeps the appearance of the original regulator box. About $95 from Wilton Auto Electrics,


Thanks all for your comments. I didn't want to go to an alternator yet. You've answered my questions.
J Butler

This thread was discussed between 08/05/2013 and 11/05/2013

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