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not enough valve adjustment

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  • not enough valve adjustment

    Due to some engine modifications, such as reground cam, resurfaced lifters and a set of modified large valve heads of unknown source, there is not enough adjustment in the rockar arms. I need longer push rod or longer adjustment screws to take up the approx 1/8" gap from what it was when stock. My thought is to shorten the rockar arm stands by the needed amount to get things back to normal and maybe have better angles on the valve train. Can bad things happen if I go this way or is ther a better approach?

    Ken

  • #2
    Depending on what year the engine is , there are two different length pushrods. About a quarter of an inch difference.

    Jamie McLeod
    Hope Mills, NC
    Jamie McLeod
    Hope Mills, NC

    1963 Lark "Ugly Betty"
    1958 Commander "Christine"
    1964 Wagonaire "Louise"
    1955 Commander Sedan
    1964 Champ
    1960 Lark

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    • #3
      FWIW, custom length pushrods are around $100. Several of us are getting ready to order some. How long are your pushrods and what length do you think you would need?

      thnx, jack vines

      PackardV8
      PackardV8

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      • #4
        The fast way of doing this would be to have a QUALIFIED machine shop cut your rocker stands. I did a Ch*vy valve conversion on my 259 many years ago which required cutting the rocker stands. It worked great. I also cut the push rods with a tubing cutter and popped the push rod end back in with a hammer. No, I'm not kidding. It worked fabulously. That was the engine I built with Dick Datson's ideas. Milled the heads 1/8 inch, Ch*vy valves 1.88 intakes and 1.5 ex., R1+ cam, aluminum timing gear, and ported intakes and exhaust ports, all gasket matched with hogged out exhaust manifolds. Drove it like I stole it for about 6 years. Then came the R1 289 which it still has. Many years of fun still to come too.

        sals54
        sals54

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        • #5
          You better check the valve to rocker alignment first. You have to make sure that the rocker doesn't go too far in either direction across the valve stem when the valve opens and closes. Cutting the stands is probably the way to go, but I would stick a longer pushrod in the intake and exhaust for a trial and see where the rocker scrubs. Incorrect geometry can cause premature rocker wear and excessive lateral movement of the valve withing the guide.

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          • #6
            I don't know what year engine you have but if it is a '51 to early '60, you have longer adjusting screws in the rocker arms than the later engines. If you then get push rods from an engine from the late '60 to '64 these have longer push rods. This might be enough to fix your lash problem.

            If you have the late '60 to '64 engine, then you might be able to use earlier rockers with the longer adjusting screws. These changes will get you about 5/32" more adjustment.

            Unless you are looking for all out performance, I don't think there would be enough geometry error to bother anything.

            Ted

            quote:Originally posted by jd-stude

            Due to some engine modifications, such as reground cam, resurfaced lifters and a set of modified large valve heads of unknown source, there is not enough adjustment in the rockar arms. I need longer push rod or longer adjustment screws to take up the approx 1/8" gap from what it was when stock. My thought is to shorten the rockar arm stands by the needed amount to get things back to normal and maybe have better angles on the valve train. Can bad things happen if I go this way or is ther a better approach?

            Ken

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            • #7
              As Sal mentioned, if you have access to the longer six push rods, it is fairly easy to shorten those to the length you need.

              Ted

              quote:Originally posted by Chicken Hawk

              I don't know what year engine you have but if it is a '51 to early '60, you have longer adjusting screws in the rocker arms than the later engines. If you then get push rods from an engine from the late '60 to '64 these have longer push rods. This might be enough to fix your lash problem.

              If you have the late '60 to '64 engine, then you might be able to use earlier rockers with the longer adjusting screws. These changes will get you about 5/32" more adjustment.

              Unless you are looking for all out performance, I don't think there would be enough geometry error to bother anything.

              Ted

              quote:Originally posted by jd-stude

              Due to some engine modifications, such as reground cam, resurfaced lifters and a set of modified large valve heads of unknown source, there is not enough adjustment in the rockar arms. I need longer push rod or longer adjustment screws to take up the approx 1/8" gap from what it was when stock. My thought is to shorten the rockar arm stands by the needed amount to get things back to normal and maybe have better angles on the valve train. Can bad things happen if I go this way or is ther a better approach?

              Ken

              Comment


              • #8
                The engine is a 63 R1 and the adjusters loose their tension and are just about out of the rockars when the slack is taken up. I just know that they won't hold the adjustment running. The push rods are 11 1/4" long and I wold need 1/8" to 3/16' longer to make it work. Looking at the arm contact at the valve when open its just the outside part of the arm holding the valve open. I can access a milling machine and might try shortening an extra set of rockars I have since it seems to be a doable solution. Thanks for the help.
                Ken

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                • #9
                  If its just adjusters you need, then those are a dime a dozen. Any other Stude V8 will use the same adjusters, so just check them before you steal them from the donor rocker arms and make sure they have plenty of tension in them before you pull them. Replace as needed on your rockers. Problem solved.

                  sals54
                  sals54

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                  • #10
                    quote:If its just adjusters you need, then those are a dime a dozen. Any other Stude V8 will use the same adjusters, so just check them before you steal them from the donor rocker arms and make sure they have plenty of tension in them before you pull them. Replace as needed on your rockers. Problem solved.
                    FWIW, The threads on the adjusting screws are an interference fit. I've known of adjusters twisting off when trying to remove them from a rocker. I'd be concerned removing one and installing it into another rocker would at the least lessen the self-locking interference fit to the point it wouldn't hold adjustment. Personally, I'd replace the whole rocker rather than the screw.

                    thnx, jack vines

                    PackardV8
                    PackardV8

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                    • #11
                      Jack, the only problem with that is the contact with the valve. I changed the screws only so I would not alter the contact patch between the rocker and valve.

                      sals54
                      sals54

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                      • #12
                        It sounds like shortening the rocker stands is the best solution, if only the very end of the rocker is touching the stem at max lift. Out of curiosity, could you possibly post a pic?

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                        • #13
                          Creating another problem (hacking up the stands) because of a problem (bad or too short adjusters!)....

                          Boy....I'd never knowingly create a second problem (or ruin one part to fix another part!) because of a first one. Do it right...what ever your method...longer push rods are in order.

                          Maybe that's just me...!

                          Mike

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                          • #14
                            It sounds to me like the valves are too short. That's why I wanted a pic of the rocker/valve contact at max lift. And in that case, the stands should be shortened.

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                            • #15
                              I measured the installed valve heights and the modified valves in my cylinder head are .210" shorter than the stock valve height. That accounts for having not enough adjustment in the rockar arms to take up the slack. I think the engine will be happier if I remove some material from the rockar arm stands because the valve train geometry will be closer to stock that way. Ken

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