1. ceebuddy

    ceebuddy Well-Known Member

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    I didn't find anything using the search so I am asking:

    I have a 71 Chrylser with a 440 engine with A/C. So there is a double belt driving the A/C-compressor and the alternator.

    I replaced the faulty alternator with a remanufactured unit. I assume the alternator I replaced is the original unit.

    When I compared the two alternators I noticed that the pulley diameter of the original unit is larger in diameter (a little over 3" outside diameter) than the pulley on the remanufacured unit (a little under 2-1/2" outside diameter).

    After I installed the new alternator I was tightening the belts when I noticed that the adjusting bolt on the alterntor is all the way at the end of the corresponding slot in the bracket. The entire setup works (the alternator very nicely charges the battery) but but the belt tension could be higher.

    I must admit that the belts look okay but pretty old so I should be replacing them soon, anyway.

    All listings mention a set of two 59" belts for this applications.

    I would like to know if someone of you already had the same issue and how you addressed it: Should I buy 59" belts or should I buy belts that are a little shorter, now that the pulley is a little smaller, too? I would like the possibility to readjust belt tension should the belts lengthen over time and I do not want to change the bracket.

    Thanks in advance for your help!
     
  2. commando1

    commando1 Mr. Normal FCBO Gold Member

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    You have the "overdrive" pulley. Good for around town. Not great for highway.
    If you are at the end of your adjustment, swap to a smaller belt. Absolutely.
     
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  3. Ross Wooldridge

    Ross Wooldridge Senior Member FCBO Gold Member

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    The alternator for AC applications did have a smaller pulley, especially in cars with lots of accessories. The smaller pulley allowed the alternator to turn a bit faster at idle, to help the alternator produce a nice fat voltage at low engine RPM.

    The bigger pulley dual belt alternator you replaced was likely a replacement from long ago... they're supposed to smaller cad plated dual pulleys on your car.

    So... there should be two bolt holes in your alternator adjustment rod, along with the long slotted hole that bolts to the block near the thermostat. Switch to the one furthes from the middle - it should give you another inch or more of adjustability. This was there to allow for that very difference - belt stretch, and different pulley sizes.

    See the pic below where the alternator adjustment rod is bolted to the alternator in the inner most hole. To get the maximum belt tension without going to the end of the slotted section by the thermostat switch to the outermost hole instead:
    ALTERNATOR MOUNT.jpg
     
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  4. commando1

    commando1 Mr. Normal FCBO Gold Member

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    Ross, the bracket you show is confusing me.

    [​IMG]

    Screenshot_2017-03-12-16-00-10-100.jpeg
     
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  5. Ross Wooldridge

    Ross Wooldridge Senior Member FCBO Gold Member

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    Hmmm ... on my car the slot is on the thermostat end. I can see that reversing the tensioner rod wouldn't work as pictured on your setup. However the solution is basically the same - move to the other bolt hole and there'll be an inch more adjustment available on the belt.
     
  6. commando1

    commando1 Mr. Normal FCBO Gold Member

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    Yah, see what I'm saying? Don't recall ever seeing the bracket installed the way it is in your pic.

    Screenshot_2017-03-12-16-23-30-924.jpeg

     
    Last edited: Mar 12, 2017
  7. Ross Wooldridge

    Ross Wooldridge Senior Member FCBO Gold Member

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    As far as I know the way it's shown in my pic is correct for 65 - 66 and I think 67 and 68 AC big block cars. That's a pic of Rexus' motor.

    I am not sure on later years, such as shown in your pic.
     
  8. commando1

    commando1 Mr. Normal FCBO Gold Member

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    The number of Mopar brackets and combinations out there can make your

    [​IMG]
     
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  9. Ross Wooldridge

    Ross Wooldridge Senior Member FCBO Gold Member

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    Agreed 100 % !

    Lol...
     
  10. commando1

    commando1 Mr. Normal FCBO Gold Member

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    Just this minute I saw this in another thread.

    PicsArt_03-12-04.53.01.jpg
     
  11. Ross Wooldridge

    Ross Wooldridge Senior Member FCBO Gold Member

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    Well there ya go! :lol:
     
  12. LatPeahy

    LatPeahy Active Member

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    I think the tensioner on my 65 NYr is backwards then. I'll have to reference it
     
  13. Ross Wooldridge

    Ross Wooldridge Senior Member FCBO Gold Member

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    They often get reversed because in reality it's a pain in the arse to have to reach over to lock the tensioner in place at the the thermostat bolt... one has to keep tension on the alternator at its' pivot plus reach in to put a wrench on the bolt.

    However, when it's reversed the long part is a knuckle gouger as it sticks out unnecessarily far past the alternator.
     
  14. LatPeahy

    LatPeahy Active Member

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    I do have it on right
    image.jpg
     
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  15. vdk2010

    vdk2010 Senior Member FCBO Gold Member

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    Why is that? I don't understand what's the disadvantage while on the highway?!
     
  16. Ross Wooldridge

    Ross Wooldridge Senior Member FCBO Gold Member

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    Personally it's not so bad in my opinion... it's just a rule of thumb that it's always better to avoid spinning accessories too fast. It generally applies to AC compressors. However, I don't think the factory would have put the smaller and faster pulley on their alternators if it were an issue.
     
  17. commando1

    commando1 Mr. Normal FCBO Gold Member

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    The alternator is spinning at a higher rpm with that smaller pulley.
     
  18. Snotty

    Snotty Senior Member FCBO Gold Member

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    That's fascinating! I'm going to check that on mine.

    Before I moved from Bakersfield, I had Chris "The Doctor" put new belts on my Newport. He told me I had 383 belts on it instead of 440 (length differences). OK, fair enough. However, they have screamed under hard acceleration ever since; they didn't do that before. I'm going to check to see where mine are as I've been temped to replace these with the shorter belts I had on before.

    Thanks!:thumbsup:
     
  19. Ross Wooldridge

    Ross Wooldridge Senior Member FCBO Gold Member

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    Belts shouldn't scream ever... often it's the idler on AC equipped cars as it's a challenge to get that belt tight enough with that silly 1/2" drive socket port...

    If they still scream after tightening try belt dressing, or lightly sanding the pulley grooves and the edges of the belts.
     
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  20. vdk2010

    vdk2010 Senior Member FCBO Gold Member

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    And that leads to more wear, ok. But that's the only downside? Or is there another technical one?