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MG MGB Technical - GM Alternator

I received the following request yesterday. Is there HANDY info available on this BBS?

Thanks in advance...
*****************************************
Rick

My son has a 79 B and he wants to convert to a GM alternator.
I know I have seen printed instructions on that but have looked and can't
find them anywhere. Do you know a site or place he can get the info he
needs?
Electrical in not my strong suit. 79 have the start and run relays.

Keith
******************

rick
rick ingram

Rick:

Somewhere in the archive should be a link to instructions for converting an MGB to the Delco alternator used on Saturns.

I made this conversion and have been very happy with the result. The instructions give you the steps to reclock the alternator housing to get the bolt holes to line right up to the mounting brackets on the engine block.

Hope this helps.

Ken V.
'77 MGB
Safety Fast!
Ken Vandruff

Here it is:

http://www.mgexperience.net/article/delco.html


Ciao,

JGC
Jean Guy Catford

Try Bob Muenchausen's web site for a variety of MGB alternator conversion and links.
http://www.cibolas7.net/4436.html
For a Lucas to Delco try this link. It has photos and tells what is needed and what has to be modified for the conversion.
http://www.teglerizer.com/alternator/index.html

Clifton
Clifton Gordon

Thanks, guys!

rick
rick ingram

Try onefastmgb.com . I found this site to be outstanding when I did the conversion on my 79 a
few years ago. Davy
Davy Crocker

Bob Muenchausen's page is linked to onefastmgb, so you get it all by going to Bob's site. I did mine as per onefastmgb; it was very easy and it works great.

Having said this, there is nothing inherently wrong with a Lucas alternator and I've gotten along fine with them for over 20 years. But if your car includes some upgrades not countenanced by the good folks at Abingdon, these high-output units are terrific. I have A/C, two electric condenser fans, and halogen headlights on my GT and the Saturn unit handles them all without breaking a sweat. I can run everything on the car while idling at a stop light at night and the turnsignals still function normally.

Don't forget that the high-output alternator will do you no good unless you upgrade the wiring from the alternator to the starter solonoid. An 8 guage lead is good; failing that, a pair of 10s.

Also, with such a system, it becomes very useful to install a voltmeter. It's become one of my favorite gauges.

FWIW,
Allen
Allen Bachelder

I have to concur with Allen 100%. Well, except for the Lucas part - I changed to the Saturn because of Lucas 'mortality' issues.

My Saturn alternator was installed about 2 years ago (15k miles on it now) on my 78 B daily driver and has been absolutely flawless. It's even keeping my 10 year old battery alive. That's something considering all of the -10*F temps we've had over the last couple of weeks.

Tom
Tom Sotomayor

Allen, I just did the conversion last weekend. Have not started the car yet because it is just to cold here. I see that you suggest running an 8 ga. wire from altenator to starter solenoid. Nothing like this was mentioned in the instruction I found on the internet. Could you explain what the purpose would be and where exactly on the alternator and the starter solenoid I would attach the wire. Thanks.
S Delph

There are lots of alternators out there that are modified or can be easily modified to be a one wire alternator.

It simplifies the wiring and works just fine in my experience.

Barry
Barry Parkinson

S Delph -

It's a matter of how much electrical "load" (amperage) a wire will carry. I know it's not mentioned in the instructions, but if your electrical loads at any one time exceed what the Lucas alternator used to put out, that 105-amp Saturn alternator can produce the current, but the original brown wire(s) from the alternator to the starter solonoid cannot carry it. I think the larger of those wires is a 12 ga. If your Saturn alternator is like mine, you connected the heavy brown wire to the binding post on the back. I'm recommending that you run an "extra" wire duplicating the path of that brown wire from the binding post on the Saturn alternator to the post where that brown wire attaches to the solonoid. When I did this, I couldn't find an 8 ga., so I ran two 10 ga wires instead, and then I ran a third 10 ga wire to spade lug on the fuse box where the brown wire connects.

It's like they built Inertstate 81 parallel to old US 11. They both go the same places, but the interstate will handle a lot more traffic. If your penchant for neatness and simplicity demands it, you could remove the old brown wire you're replacing, but I'd just as soon leave it. Certainly the redundancy doesn't hurt anything.

Whether or not it's in the instructions, I think most others on this thread will agree with me. Perhaps one of you electrical engineers can explain it a little more elegantly.

' Hope this helps.

FWIW,
Allen
Allen Bachelder

I did the same as Allen and added an extra wire between the alternator and starter solenoid. Work had an 'extra' piece of 8 ga. so that's what I used after soldering/crimping on ring terminals.

About the only thing Allen didn't mention is if the wiring is too small for the load, the wires will start to heat up. Get them hot enough and the insulation will melt or burn (electrical fire). I didn't want that kind of excitement in my life!

Allen -
Might I suggest you drop a note to Darryl outlining the additional wire(s)? I know he appreciates input about the conversion and will include it on his site.

Tom
Tom Sotomayor

Allen - point take, but you said "It's like they built Inertstate 81 parallel to old US 11. They both go the same places, but the interstate will handle a lot more traffic." Have you driven I-81 recently? Yuck.

R.
Rick Stevens

Hey Rick,

And why do you suppose I moved to Michigan! You're absolutely right about I-81. And when frequent accidents bring I-81 to a standstill near where I used to live in Virginia, the traffic would often be re-routed on US 11. The total congestion perhaps illustrated my point even better. But what's a Californian like you doing on I-81? So now they're considering making I-81 six-lane throughout Virginia. It's like doubling that 8 gauge wire. Unfortunately, to stretch my metaphor, I-81 is up to more like 300 amps.

And Tom -

Of course you're right and I neglected to mention it. A single 12 gauge wire will only carry so much Lucas smoke; if the smoke pressure gets too high, the wire bursts to let the smoke out. And as we all know, where there's smoke, there's fire. This wouldn't be an issue if the electrical load remained stock. But with A/C, halogen headlights, extra cooling fans, and maybe a high-powered audio system, there's a demand for more amps than you can cram down that single 12 gauge wire. I will write to Darryl about it.

FWIW,
Allen
Allen Bachelder

I'm kinda bi-coastal. I'm in Monterey for 18 months (native Californian), but "normally" live in Marshall, VA - off of I-66. I've spent WAAAAAYYY too much time on those roads. ;)

R.
Rick Stevens

Why would you want a one-wire? You lose the diagnostics of the warning light.
Paul Hunt 2

This thread was discussed between 07/02/2007 and 16/02/2007

MG MGB Technical index

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