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Discussion Starter #1
I’ve read several posts on this and understand the principles but I want to make sure I get it correct as I know I need to bypass the regulator.

I’m swapping 2L with alternator into my ‘69 giulia Ti 1300 that came with a Bosch generator. Photos of the new alternator and of generator are attached. Generator posts labeled D- and D+; alternator has B+, DF, D-, and D+

Would someone mind pointing me to or sketching e a simple wiring diagram?

Thanks.
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The Alternator in your picture is an early, external-regulator unit. They work fine, but you’ll need to get the correct regulator and harness to complete the installation, then find a spot to mount the regulator, etc.

There are alternatives...

The most straight forward is to buy a later alternator with integral-regulator. I think the Bosch rebuilt number is AL57X, but you’ll want to double check that. Might be AL16X. I used to know this stuff.

Once you get an internal-regulator type alternator, the wiring is relatively easy. You can leave your original regulator in place, but relocate the D+ wire from its original location to the main-bus output terminal. This D+ wire should also be connected to the alternator’s B+ output lug.

IIRC, the AL57 also has an output for your generator warning light. You may need to map out how to connect this to the lead currently connected to that light.
 

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BTW, I’ve also done Nippondenso installation on Alfas. Works fine, sometimes less expensive, certainly lighter. However, it usually requires bushings to align the pulleys and adjusting arm.

I may have these bushings in stock.
 

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Discussion Starter #4
Thanks. It sounds like getting an internal regulator alternator is the simplest solution.
 

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Could be. I’ve seen listings for the AL16 describing it as being both internal and external regulator. I always thought it was external, so am wondering if rebuilders are trying to surreptitiously delete the external reg version. Bosch themselves would not do this, but aftermarket rebuilders might try.

Over time, Alfa had different length case bosses to accept the alternator mount. The generator versions all had two ears to straddle the boss. Initially, the Alternators had two ears to straddle the boss. Eventually, most of the world went to a fat, single ear, and Alfa did that on some models.

I can still recite from memory most of the part numbers to overhaul a VW engine, but the more recent stuff has dimmed a bit.

I’d triple check the 16, and make sure you’re getting the internal reg alternator that fits. Much easier wiring.
 

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I’d triple check the 16, and make sure you’re getting the internal reg alternator that fits. Much easier wiring.
Whatever model number the internally-regulated Bosch alternator carries, you want the model used on the S3 and S4 spiders - the spiders from the late 1980's and 90's. Those are internally regulated, will fit any 105 front cover without spacers and should come with a V belt pulley.
 

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The S3 alternators were all, or mostly, internally regulated.

it gets foggier with S2s.
 

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Discussion Starter #9
It looks like the Bosch AL16X was with the Spider from the mid 70s until 1994. I have figured out wiring the B+ power side; I still need to figure out what to do with the D+ connection. I'm sure the answer is buried somewhere in here:
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I think the D+ is the one you’ll connect to the dash warning light.
 

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It looks like the Bosch AL16X was with the Spider from the mid 70s until 1994.
No, something's wrong there. In the mid 70's, Alfa alternators still had external regulators. By 1994 they were internally regulated. BNR says 1988 was the first year for internally-regulated alternators. My point is that it wouldn't be the same part number for the whole 115 series.

Don't expect a non-Alfa parts supplier, like Rock Auto, to be aware of this level of detail.

Here's a link to the late spider alternator on BNR's ebay store: Alfa Romeo Spider Milano GTV Alternator High Output 80 Amp | eBay
BNR's price ($223.49) seems a bit outrageous and many people criticize BNR's quality. So I'm not recommending that you buy from them (though I've had good luck with their stuff, though their prices seem to have climbed). Another strategy would be to get one from APE and have a local electrical shop rebuild it. Or just take the chance that it will work OK for the forseeable future.
 

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Discussion Starter #12 (Edited)
The BNR shows this as part AL16X. I ordered the same, but from another supplier. Bypassing the old regulator to the power lines (red upper right) to the battery and elsewhere is straightforward. Connecting the D+ wire is still uncertain for me. The old regulator has a D+ input wire (green lower left) but the only output wires are the power and a green output wire (lower right) labeled 61 on the regulator. Could this be where I jump the alternator D+ connection to? Is it necessary to wire over to the coil or another “stimulator”?
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