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Technical 8 ba ford flathead crank pulley question

Discussion in 'Traditional Hot Rods' started by Darin Younce, Aug 20, 2020.

  1. Darin Younce
    Joined: May 8, 2019
    Posts: 585

    Darin Younce

    I have a pulley off of another 8ba that I am installing on an 8ba I bought from Dennis Frings , it is off the engine that I have at the machine shop so I know the pulley is correct . My question is concerning both the crank key and the inside diameter of the pulley. The front of the pulley ( where you install the large bolt and washer ) has the exact diameter of the crank end and fits snug, further back on the inside of the pulley the inside diameter is a bit larger and does not fit snug to the shaft and this is where the crank key lays on the crank shaft so I am wondering why this area is not snug . The key on the crank barely engages with the key slot on the pulley at this point. I have placed the pulley on the engine and with it bolted hand tight, the pulley lines up perfectly with the water pumps . As far as really tightening , I have yet to do this and perhaps it will work fine once I do but I was going to get a new key and didn't wont to fight getting this one back off . The key that is on the crank now sets or sticks out perhaps a 16th of an inch which seems quite shallow . I will replace the key with a new but even then , the inside diameter of the pulley in that ares is a bit larger and seems like it should be snug like the front portion. I thought I had pic of this but will add some in just a little while. Thanks Darin
     

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    Last edited: Aug 20, 2020
  2. Darin Younce
    Joined: May 8, 2019
    Posts: 585

    Darin Younce

  3. Mac VP
    Joined: May 13, 2014
    Posts: 364

    Mac VP
    Member

    The bore of the pulley hub should be the same diameter from front to rear. The pulley should have the same fit as you tap it onto the crankshaft. Clean and mic the crankshaft snout (in several spots) to make sure that it’s not worn down for some reason. Most likely the wear issue is the pulley since it’s the softer metal. If you decide to replace the pulley and key, we keep them in stock.
     
    irishsteve likes this.
  4. Darin Younce
    Joined: May 8, 2019
    Posts: 585

    Darin Younce

    Thanks, I think I will go ahead and order one , not sure why the pulley I have has a larger diameter on the back end vs the front end, it really looks like it was made this way ( see 1st pic) you can see a def edge up in the pulley where the diameter changes .
     

  5. 55styleliner
    Joined: May 11, 2015
    Posts: 558

    55styleliner
    Member

    Looks fine to me. I believe mine was the same way.
     
  6. GOSFAST
    Joined: Jul 4, 2006
    Posts: 254

    GOSFAST
    Member

    Hi Darin, the bore I.D. on the pulley should be 1.313"/1.314", anywhere in between is fine!

    The crank snout (OEM) should be 1.312" (nominally), this equates to a .001/.002" "slip-fit" when installed, this is also correct!

    Thanks, Gary in N.Y.

    P.S. The bore is perfectly smooth on the I.D., there should be no "steps" anywhere inside, as shown in the photo?

    Flathead Ford Balancer-ID-1.3135.jpg !
     
  7. Darin Younce
    Joined: May 8, 2019
    Posts: 585

    Darin Younce

    This is puzzling, you say yours looks like mine , which
    Thank you , this is the answer I was looking for . You and Mac both have said the same thing , I suppose the pulley I have is worn but I swear it seems like it was made this way. the step is so precise ,like it was milled or something
     
  8. flatford39
    Joined: Dec 3, 2006
    Posts: 2,800

    flatford39
    Member

    If you took it off that crank than I would be micing the crank shaft for wear. Putting a new one on a damaged crank isn't a good idea.
     
  9. Darin Younce
    Joined: May 8, 2019
    Posts: 585

    Darin Younce

    Thanks , got the pulley off another crank.
     

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