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Discussion Starter · #1 ·
Having read the "project overdrive alternator" thread through a few times now I am confused. I think I am reading that the 4.6 alternator has a smaller pulley than the one that I currently have on my 3.8 car.

Boils down to this; can I just find a pulley for a 4.6 130 amp alt and bolt it on for a decent overdrive? It does just bolt right on correct? My father thinks its pressed on, doesnt seem right but thought I would ask.

Thanks in advance.
 

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Resident Line Creator
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Hey,

I believe you need a special tool to remove the pulley off the alternator, along with the nut that holds it on. I just bought a new alternator, and have a 1 7/8 pulley coming for it to have a better charge at idle. I plan on taking the alternator across the street to Myers for them to swap the pulleys for me.
 

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Fry Rice Specialist
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autozone can swap the pulleys too.
 

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Chapter Director Coordinator
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i can too.. it's called an impact gun

i have a 4.6L alternator pulley in that goldish color if anyone wants it
 

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just use a impact gun...
 

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Discussion Starter · #6 ·
Ok I actually have access to an impact gun, so cool.

Next question, would it even be worth switching to the 4.6 pulley? How big is it? I measured my pulley to be approx 2.5 inches. Being a 3.8 and revving to all of 4500 rpm I dont think I have to worry about overspinning the alt too much but at the same time I dont look forward to the bearings in it shreiking like a turbo if I go too small on it. Any suggestions on a rational size to get a few extra amps for the stereo?
 

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Chapter Director Coordinator
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2.5" across?

the 4.6 one is bigger than that.. like 3.5 or so
 

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Discussion Starter · #8 ·
~2.5 inches is rib to rib, like where the belt rides. The actual diameter of the whole thing is like 3.5 probably. Thanks for the info. Guess I will be buying a 2.25 or so. Anyone think 10% will make enough difference?
 

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i think a bigger pulley slows the accessory down...

in the alt's case, it won't charge as much
 

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well im measuring my stock 4.6 pulley right now and its just a hair over 2.5"....and this is not where the belt rides, but the outside diameter......from rib-to-rib where the belt rides it measures 2-1/4"...that is where the ~20% extra RPMs come from (2.25/1.875)....i dont see how anyone's pulley would measure 3.5"

jmags, if your pulley is indeed greater than 2.25" rib-to-rib, then yes a smaller pulley from a stock 4.6 would help you out, but for the price of the 1-7/8" pulley, why not go with that one?
 

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Discussion Starter · #11 ·
Thanks G M. I am a little scared of the 1 7/8 because unless my math is wrong (possible) thats about 33% overdrive from current. There is still the missing variable of the crank pulley which I haven't felt like measuring. I might just wait until th3subl3on3 gets his done and then go for it. He's like 1 mile away from me so its pretty accurate other than driving style.
 

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Got em to swap the pulley for me, no charge. But, the guy asked if I got a smaller belt for the difference. He said that the tensioners might not take up enough slack. I thought I read in the sticky thread that using the stock length was OK. Do I need to get a smaller belt?
 

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Discussion Starter · #13 ·
It seems like the 4.6 tensioner will take care if itself. You would have to ask Bagged89. He is the only one I know has a 3.8 with an overdrive pulley.
 

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Well I might be getting underdrive pulleys too so I will need a shorter belt anyway.
 
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