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MG MGB Technical - Alternator recommendations

Any recommendations on finding an alternator for a '76 midget? Used? New? best places/prices to buy from? ebay?


Go down to Auto Zone--Pep Boys or any of the other local places. Believe me--they can cross reference it and will probably have a new or rebuilt unit in stock, or can have one in a day. I'd never buy used electrics--a real chance taken there. Plus, buying locally, they're warrranted and they're convenient.
R. L Carleen

Bought a reman unit from outfit in S.C. that does their own remanufacturing. For a B got a 78-80 Ford Fiesta Bosch unit that doubled my amps. Don't know what works for midget.
J.T. Bamford

Moss sells brand new Lucas units part # 130-000. Nothing better then brand new. Bob
Bob Thompson

J.T., From whom did you get your altrenator? Sounds like it works well. Price? Thanx, Steve
Steve Meline


First off chuck the Lucas , pure junk, get yourself a small CS model GM alternator from a small fuel injected car. The reason is that, most fuel injection ECM s require a 5 volt reference signal for the F.I ecm at idle.The newer (CS) alternators are designed to charge at very low rpms in order for the computer to get a strong 5 volts at idle under worse case situations i.e. fan,heater,radio,wipers directional signal all going at once. I stripped all of the lucas trash off of my B years ago has run great since. FWIW

Nothing at all wrong with Lucas units. They have been around for 35 years and work well. Added to that their warranty seems to be no questions asked. I had Delco on GM cars in the 70s...never again.
What other Lucas "trash" did you strip off your car that makes it run great ?
Iain MacKintosh

I have to agree with Iain on this. I can enjoy a Lucas joke as well as the next guy, but there's nothing wrong with this stuff. What often amazes me is how well Lucas electrics work on some of these old cars that have been left idle for many years. On the other hand, my daily drivers for the past 20 years have always been MGBs. Every year I do at least one MG trip of anywhere from 2000 to 6000 miles. Yes, I've replaced an occasional starter or alternator (available in this region from Advance Auto) but even with the cars I've had 17 and 18 years, I've never repl

aced any electrical component more than once.

The only Lucas problem I've ever had that speaks to the slightest design fault would be the double bullet connector barrels. The metal "bridge" from one side of the barrel to the other is exposed to the air and will corrode and disintegrate in just 20-25 years. There should be a service item about this in the owners manual: "Every 200,000 miles or 20 years (which ever occurs first) replace all double bullet connector barrels". Also it's probably a good idea to sandblast the fusebox every 30 years or 300,000 miles.

Who else makes switches that can be disassembled, cleaned and/or repaired?

What's more, I find the color coding on the wiring harnesses makes good sense. There are a couple of wiring concerns that can be improved: the yellow wire for the overdrive on late model cars should be fused.
I've never owned one of these models but I've read of this.

I'd say that 98% of the problems that are attributed to Lucas are caused by DPO wiring. My all-time least-favorite DPO wiring stunt was found on my '76 B. Without a fuse, the hot lead for the radio was connected to the BROWN wire with (get this!) a SAFETY PIN. What's more, the pin was dangling in a way that it rested on the square-section cross bar that runs the width of the car under the dash. But for a coat of paint (that was gradually wearing away), that car would have been toast long before I bought it. And guess who would have been blamed?

My 2 worth... - Allen

PS: But alas, I have broken the silent code of MG owners. I have bragged about my MGs; surely for this I will be punished!
Allen Bachelder

No you won't Allen everything will be fine. I came home on a rope already this year and wasn't amused. Brand new SU electronic fuel pump went down 40 miles from home. Oh well just as well we had two MGs out that day with a rope in the trunk.

Iain MacKintosh

Thanks for the tip, I will check out the CS Alternator for possible mention on my conversion pages at my site,

If you have any photos of your install and anything written up as to how to do such a conversion, you perhaps could share that via some of the national/international club magazines or on your own (or even my) website.

There should be many alternatives to the OE Lucas units ~ even including later Lucas units. Technology does march on and things do get improvements, but in the auto industry, the inclusion of these is slow enough that newer units can become usable alternatives as they continue utilize well tried and cheap means to mount and integrate them into existing mechanical and electrical systems.
Bob Muenchausen

Both my cars came with damaged looms where the fuel pump wiring had shorted out somewhere at the back so I always recommend fitting a fuse to these circuits, easy-peasy with an in-line with short tails and bullets installed between the main and rear looms by the fusebox.

Cars with the OD manual switch on the gear lever are far more likely to suffer from shorted wiring than earlier modelds, but again I have fitted in-lines to mine. In the same area but between main loom and gearbox loom for cars with a steering column or gear lever switch, but a fuse with a female and a male spade can be installed on the back of the manual switch when it is on the dash and protect even more wiring.

Another 'pointless' pump bites the dust, eh?
Paul Hunt


I'm sure you have give the fuse sizes to us "all" many times in the past, but what size fuse did you use for the fuel pump, vs the overdrive? Just another item I should try to complete over the winter months, where does the time go?


Larry C. '74 B/GT
Larry C.

My last post should not be construed to mean I'm an originality purist type guy. For example, having discovered how easy it is to convert from dynamo to alternator, I'm pretty much routinely doing this. I have a greedy habit of using headlights, heater fan, windscreen wipers, brake lights and turnsignals all at the same time. And if it's at a traffic light on a hill, my right foot is busy keeping those brake lights on and I have a hard time reaching the gas pedal to rev up to turn signal function speed. (This is what heal and toe technique is all about, right?) So I have no qualms about switching to a Lucas alternator. I even used a Delco once - not due to any dissatisfaction with Lucas, but due to 63 amps of powere being available from my local auto parts store for a very modest $36. ' Took a bit of creative bracketry, but not hard.

- Allen

I too, tired of replacing Lucas alternator's and replaced it with a Bosch unit.
I know, I know, it's sacrilege.
But almost a bolt in operation. Just change the wiring plug a bit, and same V belt. double the amperage.

MG would have done better if not hanpered by...................................................................................

I'll let you'all fill in the blanks.

Ok, so my car isn't concours, nor will rubber bumpered 'B's probably ever become a classic like the chrome bumpered cars.

I auto cross mine with the Bosch alternator, Pertonix ignition, all manner of different suspension bits. Well the shocks are still the original from 1977.
If this car had a modern designed engine/transmission, it would give Miata's a run fer der' money!
Safety Fast
Dwight McCullough

Not to knock GM alternatives, but there have been reports of the use of the ubiquitous SI single wire alternators causing some folks alternator mounting arms on aluminum water pump bodies to break with varying consequences.

Some of these failures may have been from homebrew alternative bracketing, and some simply because the forces applied to the GM alternators fell outside of the structural parameters designed into the OE mountings. Many people seem to have been able to fabricate mountings for these alternators that work successfully, but I think the message from the failures is that it pays to investigate what the successful folks have done before fabricating something out of the scrap bin.

Some alternatives, like the Bosch and Lucas units are lucky enough to, by virtue of their similarity to the OE Lucas units, more or less replicate the dynamics of the OE mountings and is probably why these have been relatively successful from a mechanical point of view.
Bob Muenchausen

There's a guy in our club with an 'A, close to stock set-up, who routinely beats all but the very fastest Miatas.

I've never had to replace a Lucas alternator in my 20 years of MG ownership. If your electrical system is put together the right way (using the wiring diagrams helps with this) and the components are in good shape, there should be no problem. All of my "Lucas problems" have in fact been due to 25+ year old connections, etc.(whoda thunk?) and DPOs that thought they knew something about car wiring, mostly DPOs. If you need more amps, that's fine but its not Lucas' fault that you're running more electrical stuff or whatever it is that leaves you requiring more juice out of your alternator.
Wade K

Wade, I will admit to some wiring problem's with my '77.

Hey what club are you in?
We had a fella come to one of our autox's a few years back from the Chicago region, drove an 'A' He beat many cars, including me.
Maybe I should do something about the 'loose nut behind the wheel'

Here's my club web-site;

And I do admit I can compete against many newer, supposedly faster cars.
185X55X14 Kumho Ecsta V700's on 6" rims with a 1" outset really help.
Safety Fast
Dwight McCullough

"There's a guy in our club with an 'A, close to stock set-up, who routinely beats all..."

That has to be Barney Gaylord:

Jerry Causey

Dwight, I'm in the Chicagoland MG Club and that would be Barney that I'm talking about. I've got plenty of 'work' to do on the nut behind my wheel. I use quotes because autoXing is just too damn fun to be called work.
Wade Keene

This thread was discussed between 22/11/2004 and 27/11/2004

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