MGB Contemplating a conversion

DrEntropy

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• Oct 21, 2018

• #1

The charging system in our B is giving me fits. Put a new set of brushes in the generator a month ago, the voltage output was fine for a month. Last Wednesday the voltage dropped to battery voltage and no higher. Out with the genny, brushes looked fine, polished the commutator and reinstalled... no joy. Have a NOS regulator on the shelf, swapped out the older one, and again, no joy. Matter of fact the iggy light never went out so I assume the NOS regulator sat too long in the box and the points on the right side coil are stuck closed. Dressed the points in the original regulator, put it back in and still no charge. grrrr...

To eliminate the whole durn'd problem I'm thinking of going with an alternator conversion and a "dummy" regulator. Car is already changed to negative ground, did that with the rebuild a decade ago.

Anyone done this swap on a pre-'68 B? Really a straightforward conversion but not cheap. It'll put a real dent in me CAB budget.

 

Grantura_MKI

Darth Vader

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• Oct 21, 2018

• #2

Simple job. Just use an alternator that has a internal regulator...74-75ish B.

 

OP

DrEntropy

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• Oct 22, 2018

• #3

Grantura_MKI said:

Simple job. Just use an alternator that has a internal regulator...74-75ish B.

Click to expand...

That's the plan.

 

Grantura_MKI

Darth Vader

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• Oct 22, 2018

• #4

You won’t look back. Do you have an amp dial fitted?

 

OP

DrEntropy

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• Oct 22, 2018

• #5

Just a voltmeter. Made up this console for it and a clock:

 

Grantura_MKI

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• Oct 22, 2018

• #6

Excellent idea.

 

Brinkerhoff

Jedi Knight

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• Oct 23, 2018

• #7

Spiffy console !

 

P

pdplot

Yoda

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• Oct 24, 2018

• #8

Very prefessional, Doc.

 

OP

DrEntropy

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• Oct 24, 2018

• #9

Thanks, guys. Saw something similar someplace on th' innerwebs, years ago. Finally got a burr under me saddle and put this one together. Still need to do a bit of "fine tuning" to make it acceptable to me. Likely a "charging port" (a.k.a cigar lighter) in there someplace.

 

OP

DrEntropy

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• Nov 21, 2018

• #10

The deed is all but done. Took a couple hours at a leisurely pace. Got the rear bracket from Moss from their "conversion kit", sourced the alternator locally, the 'fake regulator' is due to be delivered later today. Did a bit of fettling with the coil mount instead of drilling more holes in the inner wing. Measured and relief cut the original bracket on the motor mount. Rerouted the wiring with a pair of male-to-male spade connectors for the indicator light/field lead, had to fab up a three-blade spade connector from some scrap bits of aluminum sheet for the three power leads. Now a reliable 14V steady electron flow. When the fake box arrives it'll take about ten minutes to put it in place. Could probably have 'converted' the real regulator but didn't want to cobble it.

The coil bracket is difficult to see, but it was cut on the band saw, parallel and even with the top of the motor mount for about three inches and angle-cut at just under a forty-five degree angle toward the coil end:

The 'bodge' with the wiring until the fake regulator gets here:

 

OP

DrEntropy

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• Nov 21, 2018

• #11

Heheee... postman arrived, I opened the package and swapped out the cover on the "fake" with the cover of the original. Ignition on, started the engine, no smoke, all good! The dummy is fitted inside with a 50A fuse. Very clever do! And it took UNDER ten minutes. :wink:

 

Grantura_MKI

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• Nov 21, 2018

• #12

Hoping you never need 50amps........

 

Mickey Richaud

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• Nov 21, 2018

• #13

Nice job, Bubba! :thumbsup:

 

OP

DrEntropy

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• Nov 21, 2018

• #14

D said:

Hoping you never need 50amps........

Click to expand...

As the new alternator is rated at 45 Amps, my mind is unconcerned. :smirk:

Brer Mick said:

Nice job, Bubba! :thumbsup:

Click to expand...

Thanks. I try. :wink:

 

PAUL161

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• Nov 22, 2018

• #15

What a nice job Doc! I've been contemplating installing an alternator conversion for the TF, using one that looks like the generator, they also have a fake regulator that looks like the original, with the driving lights on and the heater, it has all it can do for the generator to keep up.
This one,
View attachment 56340

 

Gliderman8

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• Nov 22, 2018

• #16

Nice work doc!

 

drooartz

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• Nov 22, 2018

• #17

Nice work, Doc.

 

OP

DrEntropy

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• Nov 23, 2018

• #18

Thanks, fellas. Appreciate the comments.

I think if I'd seen Paul's T-series alternator disguised as a generator sometime earlier I may have bit th' bullet and paid the price for one of those. There are some clever lads producing these things, wish I'd thought of doing it! Must be a market for the stuff, has to be an investment in producing them.

The purist in me kinda balks at seeing an alternator under-bonnet of the B here, but as a practical matter I've already changed many of the "correct" components and an MGB is hardly a rare collector car. This one was intended to be a driver. I've tried to build in reliability over originality. If anyone is of like mind, I would heartily endorse an aluminum radiator swap, as well. In summer here it now will idle in traffic and not give me angst as I watch the temp gauge. I also fitted an electric fan with a thermal switch to kick it on at 185°F and an override switch on that console pictured above.

Thinking I'll run it "outside th' yard" sometime next week, make a 100 mile round trip to Sarasota to help my pal down there sort some electrics on a P-5 Rolls.

 

drooartz

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• Nov 24, 2018

• #19

DrEntropy said:

I've tried to build in reliability over originality.

Click to expand...

I'm a big fan of this approach -- functional changes are welcome. Many of the changes happened in later cars (like mine, factory with alternator) anyways.

I did the aluminum radiator a few years ago, a nice upgrade for sure. May consider an electric fan at some point as well, given the heat and altitude I deal with.

 

OP

DrEntropy

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• Nov 24, 2018

• #20

With the one here, in traffic it gets turned on to run continuously and the temp stays at thermostat temp. Big improvement over the original setup.