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MG MGA - Generator vs. Alternator?

Is there a big difference in reliabilty in going from a generator ('61 MGA Roadster)to an alternator? Is the switch complicated? Thanks!

JOHN
JW Colson

John

The conversion is easy electrically: See Barney's write up: http://mgaguru.com/mgtech/electric/ac101.htm

Also Moss do a decent write up: http://www.mossmotors.com/graphics/products/PDF/130-078MGA.pdf

Mechanically it is easy if you are running an 1800 block as it is drilled for the alternator rear bracket. The 1500 engine block does not have the correct placed holes, not sure about your 1600 engine, but I think not. So you have to adapt according to the instructions in the above URLs.

Others will advise you on the electrical advantages.

Steve
Steve Gyles

John - The alternator will provide more charging current at lower engine speeds (lights won't dim and turn signals slow while ideling at signals). Generally, alternators have a higher overall current capabilities than generators do (typically, MGA/MGB generators only have a maximum current capability of 19 - 22 amps). Alternators have ball bearings on both ends of the rotor, unlike the Lucas generators with a bronze bushing at the rear of the armature. As a result, there is not the problem with excessive bushing wear if the fan belt is run tight.

Disadvantages of alternators - they generate a high back EMF that cause a drag on the input shaft, requiring a tight fan belt so that it doesn't slip. They require the car be wired for negative ground. They are not original looking unless you get one of the special made alternators that look like a generator at BIG $$$. As you can see, the disadvantages are pirmarily cosmetic (they don't look original), whereas there are some very real technological advantages. It boils down to what you want in your car. Cheers - Dave
David DuBois

I appreciate the feedback, it is helpful. Will the generator still run halogon headlights well?
JOHN
JW Colson

I have the Wipac halogen headlights on my car and have no trouble with the generator - even with the heater blower running.
David Breneman

John and Steve
My 1500 block is drilled for the rear bracket. I did the conversion a year before I switched to an 1800.
Kris
Kris Sorensen

Over the years, I have had 2 generator bearings fail. A front and a rear. Not too bad considering the technology involvedand the age of the components.

Alternators are much more robust in this area. But one area not mentioned is the associated regulator. This does, by design, have a limited lifespan being a mechanically operated device with contacts constantly arcing. Alternators, with internal semiconductor regulators, are MUCH more reliable.

The alternator's smaller diameter pulley will take a bit more HP just to operate. And if you are using more electrical equipment (i.e. more amperage) this will add to the engine load too. A 1500 doesn't have too much power to spare.

I am running a std generator / regulator in my '56 and have no problem supplying Wagner Halogen headlights with LBC halogen taillights. Even with the heater blower running full blast.

Now, If I add a pair of subwoffers in place of the spare.......

Chuck
Chuck Schaefer

This thread was discussed between 04/06/2006 and 05/06/2006

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