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Discussion Starter · #1 ·
Hi,
I want to convert my 2G system to 3g, but am concerned that the one v-belt won’t be enough for the 3g alternator. The 2G alternator has 2 v-grooves, but the outer one was for the smog pump and was driven by the alternator. The drive pulley on the crank uses the second from outermost pulley for the alternator and the outermost is for the AC compressor. If I could find one with the same diameter pulleys, I could get a larger belt for the outer pulley and drive the compressor, water pump and alternator with it, but I haven’t had any luck finding one. Any thoughts about how to provide enough drive for this alternator?
Thx
 

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1990 Ford Mustang LX 351M powered!! Project Cherry Bomb!!
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What vehicle do you have it in? IE what are the typical loads you are gnna put on it? I swapped to a 3G alternator on my 351M and it's still got the single pulley with no issues, but then again I'm not putting a huge load on it so a single groove is no biggie for it.
 

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Discussion Starter · #3 ·
Thx for the reply. I have a small motorhome. It’s a 1987 E-350 cutaway with a 460 so I need a lot of amperage
 

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1990 Ford Mustang LX 351M powered!! Project Cherry Bomb!!
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Unless you are running over a constant 100-110 amp load on it I'd say the single pulley will be fine. Be sure to upgrade your wiring from the alternator to the battery with 4 gauge wire and a 150 amp fuse or breaker. I've got a breaker on mine but you can use either for safety. If you don't upgrade the wiring that'll put a bigger strain on the alternator trying to work against the smaller wire to the battery. Think of the wire as a water hose, larger hose better transfer of current. Might not be a bad idea to check over the rest of your system while you are at it. Ground, positive from battery, make sure they are in good shape, will make your electrical system happy 😁..
 

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I run a alt that claims to be 240A with single v belt. It slips on startup as field is engaged. I have delay circuit that should fix, just need to try it. Issue with alternators is the small diameter pulley and limited contact area.
I don't get any slip when winching and that takes all the alt can give.

math
240A *14V = 3.3kw = 4.5 hp peak
 
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FWIW, I changed my stock 460 crankshaft 3 sheave pulley to accept a multi-rib pulley to drive my large case 3G alternator, grew tired of belt whine.


 

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Consider using Ford factory mounting brackets, very sturdy and good looking. I smoothed the rough castings with sandpaper and had them powder coated. I had to change the power steering pulley, replace the AC compressor, which now mounts on top above the PS. The alternator was a direct fit and easier to access than before. All pulleys are serpentine-type.
 
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