Pushrod Problems?

Slant 6 Engines

  1. pishta

    pishta I know I'm right....

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    RAU sells 3 part numbers for a 225: PL33, PL33S and PL33H(Hydraulic). The PL33 is the same across the mechanical lifter line. The S is for 75-80 225's (cast crank and its bearings, what else changed?) but I don't know what the diff would be rocker arm wise. @slantsixdan
     
  2. Charrlie_S

    Charrlie_S Well-Known Member

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    It's possible the arms are the same (they should be) but the difference being the rear mounting hole in the shaft. That hole did change somewhere around that time frame (not sure of the exact year).
     
  3. Gramps1

    Gramps1 Member

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    Here is a couple of pictures if it helps
    I know nothing about this engine other than it was a running engine.
    Nothing had been done to it recently as far as the head goes.
    I thank you for your time. 16108176034211980465691201861529.jpg 16108176366733457691397249569693.jpg
     
  4. Gramps1

    Gramps1 Member

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    Thats very helpful .
    I should have just asked that to start with.This is what we have.
    Thanks
    16108180839816937492369014828013.jpg
     
  5. Charrlie_S

    Charrlie_S Well-Known Member

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    What nuts are you talking about? I don't see any nuts.
    From the pictures I don't see anything wrong.
    PS: when you install the shaft, make sure it is installed correctly. The oil holes should point down and towards the valve spring.
     
    Last edited: Jan 16, 2021
  6. Gramps1

    Gramps1 Member

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    We took the lock nuts off the "new"rockers.
    I guess if the oe isn't supposed to have lock nuts maybe we don't have a problem.
    We can get the lash we need its just the adjuster looks way down in the rocker.
    Thank you
     
  7. Charrlie_S

    Charrlie_S Well-Known Member

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    The factory does not use lock nuts. Just make sure the adjusters are fairly tight, so they don't move on their own. The adjusters are supposed to be an interference fit.
     
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    • KosmicKuda

      KosmicKuda FABO Gold Member FABO Gold Member

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      Charlie is the man here so I'll defer to him. But isn't 3-4 threads showing below the rocker about normal?
      The pushrods appear to be about the right length.
      Try it again without the locknuts.

      The Chrysler stamped rocker arms were somewhat of an engineering marvel when introduced. The adjusters are an interference fit when everything is right. It is probably not possible that your new rockers are brand new reproductions but rather "renanufactured" originals. Cleaned and reground pads. (Another variation contributing to clearance stack up by the way). So maybe the rocker vendor is covering their butt by providing locknuts to make up for a worn out interference fit. Leave the nuts off for now and check for torque resistance.

      With so many unknowns in that engine, you may need a custom pushrod length afterall.
       
      Last edited: Jan 18, 2021
    • circlepilot

      circlepilot FABO Gold Member FABO Gold Member

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      You mention locknuts, my 225 (1965) solid lifter engine, has no "lock nuts" on the rocker arms. The adjusters are held in place by friction. Were there rocker arms manufactured with locknuts? I haven't been able to find an example of one.
      Norm

      rockerarm.jpg
       
    • Charrlie_S

      Charrlie_S Well-Known Member

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      No
       
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      • Gramps1

        Gramps1 Member

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        I want to thank everyone for their input.
        After hearing all the good advice I've decided it's operator error.
        Thanks again
         
      • Charrlie_S

        Charrlie_S Well-Known Member

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        Just remember, no one knows everything (except me :) ) we all keep learning. Lots of help here. Don't be afraid to ask for help, if in doubt.
         
      • RustyRatRod

        RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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        I think what you are experiencing is that you have nuts on the adjusters. You're going to need to measure how much tall the nuts are and add that much length to a new sec of custom pushrods, if you're going to keep the nuts. You're probably going to have to, because if those came from Gary at Rocker Arms Unlimited,like you say, the self locking feature on the threads has been removed, so it sounds like you will indeed need longer pushrods.
         
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        • RustyRatRod

          RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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          Careful! Don't "just remove" the locknuts and assume all is well. Normally, when Gary makes that, mod he runs a tap through the rocker and runs the adjusters through a die and removes any self locking function of those threads, so all you have is the locknut that holds the adjusters tight. So inspect that very carefully. If that's the case, you will need longer pushrods. They will need to be longer by however tall those locknuts are. Without the locknuts, those adjusters should be pretty tight. I've never put a torque wrench on them, but I suspect it would take 10-15 LB FT to overcome the self locking feature and turn the adjuster. If they are "much looser" than that, I would get longer pushrods and run the locknuts. IMO, if you're building any kind of performance engine, the locknuts are a good idea anyway.
           
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          • Gramps1

            Gramps1 Member

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            I'm just not familiar with a rocker with out a lock nut.
            These did come from Rocker Arms Unlimited so thats what the deal is.
            On to new push rods.
            Thanks for your knowledge and time.
             
          • my68barracuda

            my68barracuda Well-Known Member

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            Smith Brothers is a reputable shop for custom length pushrods. There are other sellers also
            To do it right, you will need a ‘push rod length checker’ basically push rod approximately the correct length with a threaded section in the center for changing the length by screwing it in or out. They are available pre made or if you are handy with a tap, pretty easy to make using one of your existing push rods, use a fine thread bolt.
            Where are you in Indiana? I am in Indy.
             
            Last edited: Jan 16, 2021
          • RustyRatRod

            RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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            I'm not knocking John's suggestion at all. It's a good one, but IMO you don't really need a checking pushrod. I would simply mic one of the locknuts, measure the total length of one of the 225 pushrods and add the lucknut thickness to it.That will get pushrods that will be just right and you'll be using what you have, instead of buying something extra. Make sure to tell whomever you deal with that you are using the TOTAL length and not measuring down into the pushrod cup. That way you'll be on the same page and use the same measurement.
             
          • Gramps1

            Gramps1 Member

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            Thanks
            We have gotten pushrods from Smith Brothers before.
            We are in Anderson,or at least what's left of it.
             
          • Gramps1

            Gramps1 Member

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            Thats a good idea.
            We will get this engine together yet!
            Thanks
             
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