Vince, As promised this is how I did the alt installation. It took about 2
hours of work this Saturday and 2 weeks of design :-). I'm posting it to
the list for anyone else interested.
Hi list,
Way back when I first signed on the list I asked about testing a Lucas
alternator so I wouldn't buy replacement parts wastefully. Vince had
suggested a Delco alternator retrofit. There was encouragement from others
on the list and it sounded like a good idea so I decided to look into it.
So here's what happened.
BACKGROUND:
I purchased a '79 B basket case late in the summer. When I got the car home
and got it running I discovered the Lucas alternator had expired. I have a
lot of work to do to reassemble and paint the car so I worked on other
things while I thought about the alternator swap. It turned out NOT to be a
drop-in and the car has A/C which makes the project a bit more difficult
(not impossible) because the A/C compressor goes where the alt goes and the
alt mount high.
Enter one '76 B parts car. I got that one home, flat towing it behind my
Blazer. After an hour of work (cleaning the carb and dist) it too ran, and
very well (better than the 79). So now I have a parts car that's worth
repairing. "How does this have anything to do with the alternator?", you
may ask. This. I pulled the '76's alt and put it on the 79 (with the plug
from the 76). I had the Delco alt so as to not relegate the 76 to flower
pot status (or spend money that could go to the 79) I decided to fit it.
The 76 does not have A/C.
HOW I DID IT:
The key, as I discovered, to a reliable, strong and stable conversion is to
use a double groove sheave on the alt. You could use a single but then
extra spacers are required to move the unit forward to line up the belt.
1) I removed the air pump so I could see the original mounting points. The
rear one is a bolted on bracket and the front one is a boss on the water
pump. The adjusting bracket attaches to the front motor plate below the
water pump boss.
2) The mounting position of the Delco alt will be with the large mounting
lug high (on top) and the adjustment lug low (on bottom) which is usually
opposite as mounted on a BAM (Big American Car)
3) For the main (top) mounting location I made 2 tabs. 1 inch wide by 2
inches long by 1/4 inch thick (HRS bar) I tapped one 5/16-18 hole 1/2 in
from one end and drilled a 3/8 hole 1/2 in from the other end (the holes
need to be 1 inch apart on center). Same for both tabs.
4) The end with the 3/8 holes needs to be radiused to remove the pointy
corners so they won't contact the alt body or fan.
5) Attach the taps to the front (as in "front of car) of each of the
original tabs w/ 5/16 bolts. Position so they stick straight out to the
passenger side (right side) of the engine. Put a nut on the exposed bolt
threads to lock each tab in.
6) Cut a piece of 3/8-16 threaded rod 5 inches long. This will be the new
pivot for the Delco alt. Slide it thru the 3/8 holes on the tabs to be sure
that the tabs are correctly adjusted. If necessary fix them now.
7) Use four 3/8 nuts and flat washers and sandwich the large alt boss and
tabs with the nuts and washers. Feed the nuts/washers as the rod is pushed
thru the rear tab and alt. Sequence of the assembly from the front of the
engine is: nut-washer-tab-alternator-washer-nut-exposed threaded rod-nut
washer-tab-washer-nut. Snug but don't tighten it all up yet.
8) I modified the original adjusting bracket by lengthening it 3 inches
with the extent ion at a 120 degree included angle. Basically it looks like
a wide, shallow "V". I also had to grind away some material from the top of
the slot to avoid contact with the fan. Bend as required to get the slot to
meet the alt tab.
8a) An after market or junkyard bracket can be substituted. It would need
to be curved and about 6 inches long.
9) Install the belt to the front groove. Adjust belt tightness and secure
all fasteners. The nuts on the threaded rod clamp the tabs and the
alternator to make a very stable package.
10) Wiring- Cut a plug from a GM car in the bone yard. The big fat brown
wire needs a 1/4 inch ring connector. Attach it to the BAT connection on
back of the alt. The small brown wire goes to the #2 terminal (field) of
the alt plug. (On mine it is a 14ga red wire.) The small brown wire with
yellow tracer goes to the #1 terminal (indicator) of the alt plug. (18ga
black on my plug.)
That's it. No other bracing is required. If you're ever out in East Nowhere
and the alt takes a side trip you can easily get a replacement that will
bolt right on.
That's how I did it.
I plan to post the instructions with scanned sketches and possibly some
pictures when I get my MG web page up and running.
Steve Bettencourt
NAMGBR member #7-3422
'79 MGB
'76 MGB
'89 S10
Steve's HotRod World Homepage
http://members.aol.com/cruzinri
http://www.geocities.com/motorcity/speedway/4995
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