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LA Block Distributor Shaft Tooth Mismatch

Electrical and Ignition

  1. Scott19_72

    Scott19_72 Active Member

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    Hi All,

    The new Mopar aftermarket distributor I ordered in from Mancini won't seat into the bushing/gear... The old one (also Mopar aftermarket, just about 12 years old) was tapered. I called them up and confirmed I ordered the one for an LA block. The shafts are the same lengths and the length under the housings is the same. The engagement length of the tapered tooth is approximately .510" vs only .230" on the tooth with the square shoulder.

    What am I looking at here, exactly? Mislabeled box for some other Mopar application, or did they just cut the shaft wrong on this thing?

    Thanks for checking this out!


    shafts-jpg.jpg
     
  2. Steve340

    Steve340 Well-Known Member

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    The new one "looks" wrong to me. Can you send it back?
    The old one looks like both my distributors. I have OE electronic and MSD.
     
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  3. Cudakiller70

    Cudakiller70 Well-Known Member

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    Can you measure from the top of the block down to the top of the gear. See if that measurement works with step/notch?
    Also just double check that the gear is completely seated and didn’t rise up when taking out old one.
     
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  4. Scott19_72

    Scott19_72 Active Member

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    Thanks Steve just making sure I'm not crazy. It doesn't seat. And yes, Mancini says they'll sort it out for me on Monday. Just wanted to see if this rang any bells for folks who might have a way I can use it (to save me another week of shipping time). For about $130 shipped I'd like it to fit instead of tearing them both down and making one good one.
     
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  5. Scott19_72

    Scott19_72 Active Member

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    Will do, I'll measure the height out next time I'm in the garage. I was able to seat the old one just fine and the gear is still meshed correctly with the cam.
     
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  6. Steve340

    Steve340 Well-Known Member

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    A simple check for when you get to bottom of the problem. I would return that Mancini one no matter what.
    Get an idea of how much end play is in the distributor.
    Install housing and sealing gasket - nip down the body lightly.
    You should still be able to freely feel the distributor end play.
    If the end play has gone or it is bound up you would need to find out what is wrong.
     
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  7. Cudakiller70

    Cudakiller70 Well-Known Member

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    Had a distributor that wouldn’t seat, turned out the O-ring was too big. Take off the O-ring and see if it goes.
     
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  8. 413

    413 Well-Known Member

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    A friends 318 car had this problem on every distributor, and tried another drive gear same. He made a spacer for the bottom of the distributor and all is fine now. Used a gasket on both sides.
     
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  9. moparleo

    moparleo Well-Known Member

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    The picture looks like 2 different shaft lengths. RB distributor shaft is longer.
    Mopar-Distributor-Length.jpg
     
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  10. Scott19_72

    Scott19_72 Active Member

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    Thanks for measuring those out!

    These are actually the same length from the hole where you pin the collar to the base of the tooth that meets the gear. It is admittedly kind of hard to tell from the pic but I did take a mic to them both. I'm thinking it was just misboxed and am going to check back in with Mancini tomorrow. I talked to some buddies of mine who also have LA engines and theirs are like the one I pulled out too.
     
  11. Scott19_72

    Scott19_72 Active Member

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    Thanks All! It will definitely be going back to Mancini. I appreciate you all taking the time to review this - I half expected there to be some ancient Mopar secret that would have let me use it (and saved me a week of shipping). I'll update this with the solution for future reference.
     
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