Valve lash question?

Discussion in 'Small Block Mopar Engine' started by carls72dart, Jul 16, 2017.

  1. carls72dart

    carls72dart Well-Known Member

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    Hi Fabo, need your help once again. I have a 340 small block with (273 adjustable iron rockers.) It has a crane .484/.484 hydraulic cam. I heard a little tapping and reset the preload on the lifters.

    Cylinder 7 is the one I have a question on. I backed out the adjusters on both intake/exhaust. As I was setting preload, both screws only turned in a little and preload set too quick. The threads on the adjusters do not go two or three threads in. Preload was gone too fast, compared to all other cylinders.

    I ran a compression check and that cylinder came back at 125, compared to all other cylinders from 160-165.

    Just need to know what I should do now. This is all new area to me. Not running the engine, until I know it's fixed. Have been reading, it could be a burnt valve.

    Any and all help is greatly appreciated. Thank you
     
    Last edited: Jul 16, 2017
  2. Bad Sport

    Bad Sport HALF A BUBBLE OFF Staff Member FABO Gold Member

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    Do the heads have hardened valve seats. Could be a sunk valve maybe?
     
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    • MOPAROFFICIAL

      MOPAROFFICIAL Well-Known Member

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      That or bent valves. Low cyl psi on that hole. Unless the 2 are off the lifters cup..
       
      Last edited: Jul 16, 2017
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      • carls72dart

        carls72dart Well-Known Member

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        I unfortunately do not know. I purchased the engine used and was told the heads had a 3 angle valve job done on them. You would think that would be done at the same time. I'm going to look through my paperwork and see what I can find. Thank you
         
      • carls72dart

        carls72dart Well-Known Member

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        Bad sport, here is the info I have on the engine:

        1972 340 block bored .30 over with 10.5.1 TRW forged pistons w/moly rings rods resized and bushed w/floating wrist pins and new locks.

        pistons and rods balanced

        arp bolts and crank polished

        clevite 77 crank, cam and rod bearings

        windage tray

        dynagear tru roller timing chain

        crane cam 284/480 degreed

        J heads 3 angle valve job

        Comp cams locks and push rods

        Mopar perf. valve springs and adjustable rocker arms

        Edelbrock torker II intake
         
      • dadodgekid

        dadodgekid When in doubt... floor it FABO Gold Member

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        what procedure are you usning for adjusting your lifter preload? There is no "lash" with a hyd cam :)
         
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        • carls72dart

          carls72dart Well-Known Member

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          Back off adjusters so pushrod has up and down motion. Adjust the adjuster, until no more movement up/down and add a half turn to set preload.
           
        • carls72dart

          carls72dart Well-Known Member

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          I now realize I used the wrong terminology, thanks for the correction :) I just updated the original post.
           
        • JoeSBP

          JoeSBP RLTW!

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          Are you rotating the crank to unload them? Not trying to insult you, just to be sure. The whole EOIC etc etc
           
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          • dadodgekid

            dadodgekid When in doubt... floor it FABO Gold Member

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            OK, are you doing your adjusting with the cam at the bottom of the lift sequence?
            Try this, Its what I do for my .557 Solid cam and works perfect. I stole this from Dragzine! Not my work but it does work perfect everytime!

            When the exhaust valve just begins to open on the first cylinder in the firing order, adjust the intake valve by loosening the adjusting nut slightly while spinning the pushrod until you feel lash in the rocker arm. Tighten the adjusting nut until the slack is taken out of the rocker arm and pushrod. Lightly turn the pushrod with your fingers as you tighten the adjusting nut, and you should feel a point where there is a little resistance (this is called Zero Lash). Turn the adjusting nut ½-turn past this point, giving you optimal pre-load for the rocker arm, pushrod and lifter. According to Newman, “you should look for .030-.060 of preload in a typical hydraulic Lifter.” Follow this procedure by carefully adjusting each intake valve according to cylinder firing order.

            When all of the intake valves have been set to the proper valve lash, you can adjust the exhaust valves. Utilizing the same procedure as with the intake valves, you need to turn the engine over until the intake pushrod moves all the way up and rotates just past maximum lift. Now the exhaust valve can be adjusted. When all of the intake and exhaust valves have been set with the proper lash, it is common for all the top engine builders to perform a double check by rotating the engine and checking each valve again, starting from the first cylinder in the firing order.
             
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            • carls72dart

              carls72dart Well-Known Member

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              EOIC is the exact procedure I use :)
               
            • krazykuda

              krazykuda FABO Gold Member FABO Gold Member Technical Editor

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              The easy way to find that is to remove the rocker arms and see if the valve tips are all at the same height or are some higher???
               
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              • carls72dart

                carls72dart Well-Known Member

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                I use EOIC and this is the same information I came across :)
                 
              • carls72dart

                carls72dart Well-Known Member

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                Should I pull the intake and heads and check from the cam to the rockers? Didn't want to remove the head, if I don't have to! I know if it's a valve problem, the head's coming off.
                 
              • dadodgekid

                dadodgekid When in doubt... floor it FABO Gold Member

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                OK good deal, so we are on the same page.
                 
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                • dadodgekid

                  dadodgekid When in doubt... floor it FABO Gold Member

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                  So is Cyl #7 is less compression, is the adjusted bottomed out? or you barely have to screw the adjuster in the rocker to set it? maybe bounced the pushrod out of the cup of the lifter.
                   
                • 4spdragtop

                  4spdragtop FABO Gold Member FABO Gold Member

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                  Could rocker shaft be bent? Spacer messed up?
                   
                • carls72dart

                  carls72dart Well-Known Member

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                  Just barely screwing the adjuster in and it sets tight! It is the same for both intake & exhaust.....
                   
                • carls72dart

                  carls72dart Well-Known Member

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                  Spacers all seem to be positioned correctly... not sure if it's bent...
                   
                • yellow rose

                  yellow rose Doctor of Thinkology.

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                  For that tiny cam you can set the preload off the firing order. It's quicker and just as accurate. Unless you have a very long duration, high lift cam.
                   
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                  • dadodgekid

                    dadodgekid When in doubt... floor it FABO Gold Member

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                    Well if the pushrod is in fact set in the lifter correctly, Im going to guess the hyd lifter is locked up.
                     
                  • JoeSBP

                    JoeSBP RLTW!

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                    so what would be the next step? give it preload, then run seafoam through it?
                     
                  • carls72dart

                    carls72dart Well-Known Member

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                    I'm going to remove the intake and look every piece over. If I don't come up with anything there, I'll pull the heads.

                    Thank you all for taking the time to answer my questions :)
                     
                  • dadodgekid

                    dadodgekid When in doubt... floor it FABO Gold Member

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                    No problem! hope you find the issue!
                     
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                    • AJ/FormS

                      AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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                      Before All that I would recommend a leak-test on that cylinder with the valves adjusters backed off. Then after I get a number, I would lightly bop the valve stems with plastic tipped mallet; and see if the leakage number changes. If no change but the number is good, like 4 to 8% max. Then I would check the valve stem heights as already mentioned, to be sure that these two are not suddenly sitting higher than the others. And if they are similar to the others then I would swap the rockers over from another cylinder. And if that makes no difference then it has to be hydrolocked lifters. I know it's the long way around to just popping the lifters out and replacing them, but with this rigmarole you know exactly what is wrong-no guessing.
                      I too run a very light preload; 1/2 turn. Yeah they have to be adjusted more often, during the break-in; but after that they go many thousands of miles. Years even. And the payback is no lifter pump-up, and an engine that revs until it floats the valves,or starves for oil on the rods and blows up. But there are fixes for those too.
                       
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