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M38a1 24v To 12v; Delco Dual Pulley?

Discussion in 'Early CJ5 and CJ6 Tech' started by jeepljeff, Apr 9, 2024.

  1. jeepljeff

    jeepljeff New Member

    Just what the title states. I've got a M38A1 with the dual 5/8" pulleys. I'm going to be converting it over to 12v with a Delco 10Si and would like to retain the dual pulley setup. I'm guessing the alternator comes with a single belt 1/2" pulley. Is there a readily available dual pulley that will work? I'm guessing the one on the generator won't work?
     
    Glenn likes this.
  2. Dwins1

    Dwins1 Member

    Do you need to convert the pulley to a dual? The 12 v does not have the same drag as the generator. I have seen kits online. I will poke around.

    check this out. He will take your old generator and make it an alternator

    https://www.gener-nator.com/
     
    Last edited: Apr 9, 2024
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  3. Dwins1

    Dwins1 Member

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  4. jeepljeff

    jeepljeff New Member

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  5. jannickz

    jannickz New Member

    You're right on track! Converting your M38A1 to 12v with a Delco 10Si and retaining the dual pulley setup requires some workarounds. The stock M38A1 generator uses a single belt and likely won't work with your dual pulley setup. The Delco 10Si alternator typically comes with a single-groove pulley for a half-inch belt.
     
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  6. PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    ????
     
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  7. Dwins1

    Dwins1 Member

  8. Jw60

    Jw60 That guy 2024 Sponsor 2023 Sponsor 2022 Sponsor

    I know this is a topic on the antique tractor sites but it's been years since I looked.
     
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  9. vtxtasy

    vtxtasy oldbee 2024 Sponsor 2023 Sponsor

    Summit carries several flavors of double groove alternator pulleys.
     
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  10. Mr_Vaughan

    Mr_Vaughan New Member

    will the pulley potentially fit on the alternator with some work?

    also, not to completely run the thread off the rails but a 100 amp 10si might not be the best idea - the design of the 10si was only ever used up to 63 amps from the factory, anything more is an aftermarket design. the 12si was what gm used in high current applications, up to a 94 amp output. it cools much better, and mounts and looks similar
     
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  11. duffer

    duffer Rodent Power

    This. A lot of the Delco generators have the same diameter shaft as the alternators. On a couple of old tractor projects, I just used the generator pulley with the alternator "fan" sandwiched between.
     
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  12. Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member


    17 mm (where did THAT come from???) with a taper for the pulley.
     
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  13. Dwins1

    Dwins1 Member

    Question why are you removing the 24 v gen?
     
    Last edited: Apr 11, 2024
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  14. PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Yah. I think the 24v equipment is superior quality.
     
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  15. Fireball

    Fireball Well-Known Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

    But like Betamax, it doesn't really matter if it's not compatible with the 99% of everything else that's out there.
     
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  16. Oldpappy

    Oldpappy A.C. Fults - Curmudgeon at large 2022 Sponsor

    "But like Betamax, it doesn't really matter if it's not compatible with the 99% of everything else that's out there."

    Betamax was better, and in those days movies were expensive. A lot of folks built a library of movies in that format, spending a good bit of money, then the format was abandoned.

    24v might also be better, but it takes two batteries instead of just one, and it might be hard to get a jump start.
     
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  17. Fireball

    Fireball Well-Known Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

    That's exactly my point.
     
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  18. Oldpappy

    Oldpappy A.C. Fults - Curmudgeon at large 2022 Sponsor

    However, if the 24v system is in place including the slave port, you could jump start a B17 and that would be cool.
     
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  19. Fireball

    Fireball Well-Known Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

    I've had to turn several B-17s down lately because I'm only 12V. :rofl:
     
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  20. Oldpappy

    Oldpappy A.C. Fults - Curmudgeon at large 2022 Sponsor

    Granted, the opportunity to jump start a an old war plane is unlikely, it would still be cool to be ready.
     
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