Upgrading to a Delco Alternator-Buick 350

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Upgrading to a Delco Alternator-Buick 350

Post by Kaiserman » Wed Apr 24, 2013 5:38 pm

I decided to upgrade from my old Motorola to a more modern, internally regulated Delco alternator and figured I'd share some pics. It's very easy swap. You need an alternator which can be from any mid 70's to late 80's GM product. These can be found in many flavors from 37 to over 100 amps. Mind is a 55, the same rating as what the truck had from the factory. And you will need the plug for the alternator. This can be scrounged from the junk yard, or bought for a few dollars at any parts store.

First the obvious stuff. Disconnect you battery ground, remove the alternator and disconnect every wire attached to it. The green/white tracer wire and the black/white tracer wire can be cut off flush with the end of the tape on the harness. They will not have power when your done.

The Delco alternator is almost a drop in. The boss for the ground bolt (seen here at 9 o'clock) needs to be cut flush with the case or it WILL hit your lower alternator bracket. You also won't be able to use this location for the ground because of the tight fit. I never added a ground to my 71, and haven't had a problem for 10 years.


This is the stock power feed from for the old alternator. It runs to the starter solenoid and has constant battery power. It fits onto the power lug of your new alternator.


The plug for the Delco alternator has a red and a white lead. Crimp a ring terminal onto the red lead after cutting it to the appropriate length and attach it to the power lug with the yellow wire.


Unplug the stock harness from the voltage regulator. Remove and discard the voltage regulator.

Remove a bit of tape from the harness where the 4 wires that ran to the regulator come out of it . You can cut the green/white tracer wire and the black/white tracer wire flush with the harness. Cut the two grey wires (one coming from the alt side of the harness, and one coming from the vehicle side) and connect the two by any decent method. I used a non insulated butt splice and some heat shrink tube. Tape the harness back together when you are done.


Now cut the ring terminal off the grey wire you unhooked from the back of the old alternator and crimp on either a male or female spade terminal. Crimp on the mating terminal to the white lead coming from the alternator plug and connect the two. I used factory style connectors and plugs I bought from Northeast Fasteners.

Doing this allows the AMP idiot light to continue working.


All that is left is bolting the alternator up and adjusting the belt. You can re-use your old belt.\ and adjustment bracket. Chances are the new alternator will have a metric bolt, it fits in the slot for the old 5/16" bolt just fine.

Pretty simple upgrade that ends up looking pretty clean.

1971 J2500 Gladiator Custom-Cab Platform Stake on 126" wb. B350/T18A/D20 D60/D60-3 w/locker 4.10's Ramsey 8klb PTO winch, Day-brook dump. 235/85R16's
1969 J3800 Gladiator 3407Z Camper Truck. B350/T18A/D20 D44/D60-3 w/4.10's
1968 J3800 Gladiator 3406Z Custom Cab 160" wheel base dually. 24K miles. B350/T18A/D20 D44HD/D70 posi w/4.88's 7/50-16's
1963 J300 Gladiator Townside Buick 350/Th400/D20 D44/D53 4.27 gears. Stock Meyers plow, 225/95R16's

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Re: Upgrading to a Delco Alternator-Buick 350

Post by jdaniel83 » Wed Apr 24, 2013 9:10 pm

Thanks for the good write up and pics. I still need to do this on our '70 Wag. Have had the new alternator and everything for about 4 months but haven't had time, but I hope to get to it this weekend and this will help out a bunch. Thanks again!
'89 GW, 360, Skip White HEI, Melling MTA-1 Cam, Performer Intake, Summit 600 Carb, 3.73 gears, 4" Suspension Lift, 32" Wild County MTX (mine)
'70 Wag, bone stock Buick 350, 3.73 gears (my dad's, grandfather bought it brand new)
'83 Wag Limited, completely stock 360, 3.31 gears, 92K original miles (family's rig)

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Re: Upgrading to a Delco Alternator-Buick 350

Post by Kenne » Wed Apr 24, 2013 10:48 pm

i did the same to my 66, but got a 120A.
"Kelly, a tiger has only one weak point, and that's it's ass. You gotta hit it point blank and you gotta hit it from behind!"

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