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Discussion Starter #1 (Edited)
Anyone actually done it, in place of a 12si (GM small case) alt? This is going on my 70's SBC engine.

It looks like nearly a bolt-on... but how to wire it?
This is supposed to be a bad-ass 90-105 amp Bosch that can keep up with a 130+amp Delco alternator... anyone? Bueller?
 

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I'll get pics tonight. Unless someone explains it during the day.
 

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Discussion Starter #4
nice! thanks. I found I can get 'em from a yard for $30 each... Do you have into on which terminal goes to what, too?
 

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I can get some info on most anything dealing with that alt. Might want to PM Yo Mammy Boy, he was a Plant Engineer for 3-4 years at a place that remaned starters and alternators.
 

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Discussion Starter #6
will do... I really appreciate it, as no one seems to have any info on this! (except you)
 

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Discussion Starter #9
The alternator is a Bosch unit... it's not very high amperage, but it's the way it delivers it..makes it very strong. delta wired versus Y'd, or something like that IIRC.
 

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Well, here is what I am running. 105 amp (108 on the test bench) Adjustable voltage from 13-15. About all that goes wrong with Bosch units is they use brushes up. A triple wound SI would be almost as good, but the SI wouldn't handle heat as well. The clocking, and housing is almost identical to what I have on my 4.3, that had a SI. Wiring is simple:
 

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Discussion Starter #11
thanks man... so it seems as though swapping up to a bosch from a SI alt will be as easy as I thought... :D

Where do you adjust the voltage?
 

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Discussion Starter #15
I found 2 in my local boneyard... I heard the Scorpio had the bigger alt.
 

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Mekurs are junk, I don't think any survived:D Find Bosch in most German cars. You can swap the pulleys around w/o much problem. Probably can swap your current SI pulley over.

There is a little screw on it for adjusting the voltage, I'll grab a pic tonight. It should be set at 14.2.

Man, I'm foggy with this crap...I haven't dealt with this stuff since my internship 5 years ago:D

As for grabbing these from the parts store, I don't think they are cheap:eek:
 

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The wiring that LAME has illustrated is essentially correct. Most Bosch alternators are essentially the same internally. The Merkur model has higher amps then a more common version (VW Golf/Jetta).

After being around a company that builds 4000+ alternators a day, I quickly could see what is good and bad about certain alternators. The Bosch rarely had any catastrophic failures; they typically just wear down their brushes. Another common problem is the slip ring on the rotor disappears from many years of use (I have seen tons of 200K mile Benz's, VW's etc.). Plus, the Bosch is about as simple to rebuild as a 10SI. All domestic alternators suck, BUT, they are inexpensive so you can afford to have them fail.

To adjust voltage, look on the regulator on the back of the alternator there should be a small cover. Open the cover (if it is an aftermarket regulator) and you will see a small screw. Using a voltmeter you can adjust your voltage to what ever you want. Since you guys on this board insist on driving those crappy ass Jeeps and other old junk, I would recommend a higher voltage, say 14.7, in order to compensate for all of the poor wiring, bad grounds and other offending voltage drops.
 

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To adjust voltage, look on the regulator on the back of the alternator there should be a small cover. Open the cover (if it is an aftermarket regulator) and you will see a small screw. Using a voltmeter you can adjust your voltage to what ever you want.

Bringing a old thread back....I installed a Bosch 90 amp unit today and it charges at about 13.5 volts. Opened the cover and no screw. Is it just the aftermarket units that are adjustable? Any particular aftermarket reg to get?
Also what is the capacitor type thing that plugs next to where the ignition plugs in? Is it just for radio noise?
 

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Discussion Starter #20
Remember though, these are wound more for amperage than voltage.. you don't need as much V to get the pwoer you're looking for...
 
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