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Rambler American Restoration

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Retrofitting a Delco 10si Alternator

The alternator finally quit working on my American. Instead of spending the money on a stock replacement (40 amp Motorola), I went ahead and replaced it with a Delco 10si (65 amp). This procedure should be the same for any AMC 199/232/258 equipped with a Motorola alternator.

You'll need to buy the following items to do this conversion:

1 - Delco 10si alternator. They should be able to just yank one off the shelf, but if they insist on knowing what its for, pick your (least) favorite 72 to 87 rear drive GM and ask for one for that.
1 - GM style alternator pig-tail.
1 - Post type crimp connector. Get the blue ones with a medium size hole.

Solder, wire strippers, wire cutters, shrink tape/tube, wire ties, soldering iron/gun, miscellaneous sockets and wrenches.

NOTE: You will need to machine the alternator's pivot boss to allow it to fit into the factory brackets. Keep in mind that when you do this, you void any warranty the new alternator has.

Begin by disconnecting the battery and removing the old alternator.

Measure the length of the pivot boss on the old alternator and cut the pivot boss on the new alternator to this length. It is very important that you do not allow any metal shavings to get into the alternator. If you wish, you can remove the front of of the housing by removing the pulley and the 4 through bolts. Once the boss is cut to length, remove the 4 through bolts from the alternator and rotate the case 90 degrees so the wiring plug on the side is opposite the pivot boss. Reinstall the through bolts.

Once that is done, you'll need to make the following changes to the vehicle wiring (don't worry, you only need to cut one wire!): Remove the voltage regulator and cover the open connector with electrical tape. Cut the connector off of the field + wire (cut it back far enough so you can reattach it later if you want to convert back to the Motorola style alternator) going to the old alternator. On my car, it was orange. Check the wiring diagram for you car to make sure. What you are looking for is the wire that comes from the warning light on the dash. Solder this wire to the white wire on the pig tail. Crimp a post style connector on the red wire and connect it to the battery lug. Plug the pig tail into the alternator. Connect the original battery output wire to the battery lug on the alternator.

Install the new alternator. You'll need to move the upper alternator bracket slightly since the Delco alternator is slightly taller. Install the belt and tighten to specs. Cover the left over connectors with electrical tape to prevent shorts and then wire tie them out of the way. Voila! You're done!

August 4th, 2004 Update - I took my American to the "AMC's In The Park" show in Kenosha, WI this past weekend and the bearings in my rebuilt Delco gave out along the way. Luckily, Kennedy American (614-879-7283)  was there selling Power Master brand Delco style alternators that were already machined to drop into the Motorola brackets (I picked up a 100 amp unit). I did run into one problem with these alternators and that is that they are slightly wider than a Delco 10si and hit the power steering gear before the belt is fully tight. The solution was a half inch shorter belt (36 inches overall). I used Dayco belt #15360. If you have standard steering, the stock belt (Dayco #15365) should work fine.

Last Updated 08/04/04 10:43:19 PM