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3G alt swap help

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Old 11-23-2012, 01:19 AM
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Default 3G alt swap help

I finally hit my breaking point tonight as my headlights are now dimmed whenever my 1000 watts of kenwood bass hits so I am in need of a big alternator, the stock 75 2G aint doing it any more.

I am worried though about ordering a 3G alt for my 1994 4.9L and it not having the right mounts so I came here to double check.

Would this work: (http://www.ebay.com/itm/FORD-MUSTANG...60234b&vxp=mtr), as it seems to have the exact mounting holes as my stock one (offset pivot if I'm not mistaken?), or would a 3G with 12:00 position and 8.25" mounting holes work too?

Or here is a 200amp 3G with 12:00 mounts that I was looking to order but wanted to double check:

(http://www.ebay.com/itm/1996-1995-19...f70b71&vxp=mtr)

Thanks
Old 11-23-2012, 02:00 AM
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You need a capacitor.
Old 11-23-2012, 08:09 AM
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We need the year model. Some do not require modding the mounts. We have a whole thread with nearly every available scenario. Search for 3g swap. The 94-96 4.9 are a direct swap.
https://www.f150forum.com/f10/3g-alt...4/#post1944767

Edit. I missed the 94 part. Just go to oreilly or Autozone or advanced and get one allot cheaper and it should be a direct bolt on.

Last edited by unit505; 11-23-2012 at 08:24 AM.
Old 11-23-2012, 08:30 AM
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Okay...not cheaper, but here is the stock 130 amp for comparison...
http://www.autozone.com/autozone/par...0_188029_4449_
Old 11-23-2012, 09:55 AM
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505 is correct, he knows the in and outs of selecting the alt. I bought mine as a kit from RJM.

http://www.rjminjectiontech.com/collections/alternators
Old 11-23-2012, 02:47 PM
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The year model of the altwrnator? My truck is a 1994. Would either of those ebay listings work?
Old 11-23-2012, 03:46 PM
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Sean is right. If you are running a 1000 watt Kenwood you need a capacitor. The high output alternator will help but is not designed for high load on demand like that. It will strain the alternator and battery.
Old 11-23-2012, 03:49 PM
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Originally Posted by Warlockk
Sean is right. If you are running a 1000 watt Kenwood you need a capacitor. The high output alternator will help but is not designed for high load on demand like that. It will strain the alternator and battery.
I hate caps, as it never seemed to really help...had one and then got rid of it. I swear I would do the instructions exactly and still my old 1500 watt system would swamp my alt.

Thats why I was looking at a 200 amp alt.
Old 11-23-2012, 03:54 PM
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It's a system. You want upgraded alternator, battery wrong and a capacitor for everything to work right. The amp switches rapidly to a high current draw then stops then does it again. Your alternator will be switching on and off constantly as it senses the current draw. The cap prevents this. It won't help if you don't have the charging capacity, but it buffers the drain.
Old 11-23-2012, 03:55 PM
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Originally Posted by Warlockk
It's a system. You want upgraded alternator, battery wrong and a capacitor for everything to work right. The amp switches rapidly to a high current draw then stops then does it again. Your alternator will be switching on and off constantly as it senses the current draw. The cap prevents this. It won't help if you don't have the charging capacity, but it buffers the drain.
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