Early vs Late 3v Crank Pulley Differences?

Small Block Mopar Engine

  1. Tylinol

    Tylinol Well-Known Member

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    Hey everyone. I'm trying to find a suitable replacement for my '69 3-groove pulley (for my power steering/AC 1969 Barracuda). MAncini racing has one that looks like it would work CVF Small Block Chrysler Crankshaft Pulley - 3V . But, they say it's only for 70-later with the water pump outlet on the other side. For the life of me, I can't figure out why that would matter for the crank pulley. Does anyone have any insight? Could I actually use this on my '69?
     
  2. xLURKxDOGx

    xLURKxDOGx "An angel fat, at satan's feast"

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    I’ve got an early 3 groove pulley off a 67 barracuda. PM me if you’re interested.
     
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    • xLURKxDOGx

      xLURKxDOGx "An angel fat, at satan's feast"

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      The difference is the water pump. Aluminum vs cast. You can use it if you switch out the water pump from a cast to aluminum assuming you’re not already running a 70 and later pump.
       
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      • Professor Fate

        Professor Fate Push the button, Max...

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        Two things can differ:
        The pulley/balancer bolt pattern changed in '70- one bolt was staggered pre-'70, pattern went symmetrical after that. Not a big deal, file 1 hole oblong.
        Since the pre-'70 water pump (iron) was shorter than the '70 and later pump (aluminum)some of the depths/offsets could be different, depending on application- same goes for the pump pulley.
         
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        • Tylinol

          Tylinol Well-Known Member

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          Hmm, maybe it is the depth then. Although, I would think that would mean an alternator pulley or power steering pulley would be different post-70 as well. If anyone has a 70+ 3-groove pulley and would be willing to measure the depths from the balancer to each notch, I would be interested to do the same on my 69 pulley and post the results. It would be great if opening up the one bolt hole was the only difference.
           
        • mopowers

          mopowers Well-Known Member

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          The alternator pulley should be the same, shouldn't they? Did the alternator bracket offset ever change?
           
        • Professor Fate

          Professor Fate Push the button, Max...

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          Yes, for A/C cars and some trucks, maybe others.
           
        • mopowers

          mopowers Well-Known Member

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          I meant from 69 to 70 - all else being equal. In other words, since it sounds like the crank pulleys changed from 69-70, and not just the w/p pulleys. If that's true, wouldn't either the alternator pulley or bracket have to change in '70 to compensate?
           
        • Tylinol

          Tylinol Well-Known Member

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          If anyone's interested, I just measured the depths of the three groves from the base (damper end) of the pulley.
          Groove 1: ~1-1/2"
          Groove 2: ~2-1/8"
          Groove 3: ~2-7/8"
           
        • Tylinol

          Tylinol Well-Known Member

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          I might just order one of these pulleys to see if it fits. In my reading about the swap from the early to late water pump on small blocks, I only ever see mention of changing the pump, radiator, hoses, and (if you want to be able to see your timing marks) the timing cover and balancer. If changing the pulley isn't needed for the swap, I would think that means they're functionally the same.
           
        • SGBARRACUDA

          SGBARRACUDA ROY FABO Gold Member

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          69 and earlier AC was a single belt. 70 and after they used dual belt. This makes the lower pulley different.
           
        • Tylinol

          Tylinol Well-Known Member

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          So the earlier pulleys have an extra groove? Mine has three grooves on the crank pulley, which I thought was the same number as the later cars.
           
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          • SGBARRACUDA

            SGBARRACUDA ROY FABO Gold Member

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            Not sure. Only way to know what it came on is if you can find a part number on that 3 groove.
             
          • Ironracer

            Ironracer Gearhead

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            I took the 3 Groove pulls of my 66 273 ac Sat and put them on my 70s 340. No problem. But I used them all. And the water pump pulley IS right on the crank pully. Think it's was sparking once (.self clearance)
             
          • Tylinol

            Tylinol Well-Known Member

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            So I thought I'd share an update on what is becoming the most annoying saga...
            As it turns out, I do not need a 3v pulley. My Sanden compressor bracket for the peanut compressor retrofit changes the belt layout to two belts: Crank->AC->PS and Crank->Alt->WP. My 3 groove pulley lines up correctly, the third groove just remains unused. So I can use either a 3v or 2v pulley.

            According to the guy at CVF, both the pulley depth and the groove spacing are different between the earlier cars and the 70+. CVF only offers an underdrive 2v pulley (5.25") for the '69, which would be pushing it even without AC (although I do have a cold case radiator, which should help some).

            I wanted to keep the 7.25" pulley diameter to overdrive my water pump, same as the factory did. I managed to find what I thought was the perfect answer - a 3v pulley from an air-conditioned 68 Satellite 318. I'd been hesitant to buy a used pulley because my primary concern is the rubber deteriorating and allowing the middle pulley to break loose and bang things up (my understanding is that it's mounted on rubber), but this pulley was all metal - apparently they did that early on.

            So my pulley got here today, and to my surprise the inner (water pump) groove diameter is the standard 6.25. The other grooves are the same as my '69 3v pulley. Great... I can probably get away with it until May or so since the worst of the summer heat is over, though. The other issue is that this pulley is not steel like my '69 - it's cast iron and HEAVY. A good 4lbs heavier than my '69 when measured on the scale, over 11lbs total. I imagine it's going to be an absolute boat anchor at the end of my engine, so I'd be willing to eat the cost if I could find a lighter steel or billet 2v pulley in 6.25 diameter while I wait to see if I can get my '69 pulley rebuilt with new rubber.
             
          • SGBARRACUDA

            SGBARRACUDA ROY FABO Gold Member

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            I have two 2 groove listed for sale post 70. But I’m out of town for a week.
             
          • 512Stroker

            512Stroker We are all here because we are not all there.

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            Same problem
            I ended up using a March 3 groove crank pulley all the other pulleys and brackets a pre 70 including the factory A/C compressor.
            I did have a local machinist cut the A/C groove on the new crank pulley wider to fit the wider belt of the factory A/C setup.
             
          • Tylinol

            Tylinol Well-Known Member

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            Interesting, so no alignment issues with using the March 3 groove? Is there pulley listed for '69 and earlier or '70 and later engines?
             
          • SGBARRACUDA

            SGBARRACUDA ROY FABO Gold Member

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            Early uses a smaller diameter than the 70 and after. I have both for sale here.
             
          • 512Stroker

            512Stroker We are all here because we are not all there.

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            I think it is for 70 and up
            I did also have to realign the power steering pump to make it work
            So far have driven the car approx 1000 miles no issues.
            I post a couple pic's later
             
          • 512Stroker

            512Stroker We are all here because we are not all there.

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            CP1.jpg

            CP2.jpg

            CP3.jpg

            CP4.jpg
            Crank pulley collection

            CP5.jpg
             
          • Tylinol

            Tylinol Well-Known Member

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            Something just occurred to me while looking at my pulley. It appears to be the outer groove that's rubber mounted. I don't need this groove anymore since my AC bracket has the compressor and PS pump sharing the second groove. I'd like to keep the larger diameter inner groove to drive my water pump faster, so I'm somewhat hesitant to a factory 2v pulley - although I'm sure the little Sanden compressor puts a lot less demand on the system than the factory unit, I want plenty of cooling overhead.

            Even though I'm not running anything on the third groove, I have fears of the old rubber breaking loose and hurling that ring through my radiator

            What if I just burnt the rubber off of my factory 3v pulley? I would think I could then remove the third groove. That groove does have drill dimples in it that I assume are for balancing, but other factory pulleys don't seem to and I assume it's just because the rubber + third groove weighed so much. Perhaps worst case I could have it balanced at the machine shop after burning off the rubber and removing the groove. Thoughts?
             
          • 512Stroker

            512Stroker We are all here because we are not all there.

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            The rubber is there to dampen vibrations from the factory A/C compressor, it works very well. You will absolutely destroy the pulley if you try to burn the rubber out of it. FYI that pulley is a rare beast and worth way more $ than what it cost replace it. Find a good replacement pulley make sure it works then sell the factory pulley on the forum here to offset the replacement $.
            Talk to the people who made your new A/C brackets and see if they have a recommendation for the correct pulley.
             
          • Tylinol

            Tylinol Well-Known Member

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            Well I don't want to butcher any rare parts that someone else could use, that's for sure. I'll see what the largest diameter pre-70 2 groove I can find is. My math tells me that the cast iron pulley (156mm) I bought will give my WP (145mm) a 7.8% overdrive, while my original (187mm) was about a 28% overdrive. I'd love to be above 10% at least but I'll probably go ahead and put the cast iron pulley on for the moment so that I can get this engine break-in started.
             
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