340 issue after camshaft change

Small Block Mopar Engine

  1. RustyRatRod

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

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    Yeah and with them charts, you have to be very careful, because they are far from accurate for everything. Really fast ramps and really BIG camshafts cannot be adjusted using them charts, because it will not be right worth snot. Doing them one at a time right down the line has always been the dead easiest way for me. I've made PRECIOUS FEW errors using that method.
     
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    • 66fs

      66fs FABO Gold Member FABO Gold Member

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      And the base circle is not always a constant radius.
       
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      • RustyRatRod

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

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        That's completely true! S'why I like to SEE it. lol
         
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        • 12many

          12many Well-Known Member

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          I believe the 180 degree MP chart was made to be an accurate method that was useful at the track vs doing one at a time. And the other 90 degree chart is for bigger duration cams iirc. Whatever works for anyone as long as you do it right right?:thumbsup:
          I will tell you this, and I know you know, not every cam lobes base circle is accurate, many can be out of round (due to old machinery etc) as you rotate from the close side to the open side of the lobe. You move the cam one way or the other on what is still considered the base and you may find eye opening variances.
           
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          • 92b

            92b FABO Gold Member FABO Gold Member

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            According to the op both valves are open at tdc on all cylinders. Using the chart correctly and all other methods mentioned would not have that result. Even if the base circle was off a little.
             
          • fishmens67

            fishmens67 FABO Gold Member FABO Gold Member

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            What kind of lifters are you using. were they pumped up before adjusting ?
             
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            • Hellrats

              Hellrats Just another dumbass FABO Gold Member

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              He needs to give more info. My bet is his push rods are too long. He said he has adjustable rocker arms so between the camshaft and the rocker arms something will be off. It may be good he walked away for a bit. When he goes back at it he may just see what is wrong. Mom always said come back with fresh eyes. Sometimes it works. Sometimes you can't see the forest for the trees.
               
            • Hellrats

              Hellrats Just another dumbass FABO Gold Member

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              Hope the valves didn't introduce them self to the pistons at this point
               
            • 512Stroker

              512Stroker We are all here because we are not all there.

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              You would have thought that he would have noticed the push rods were to long when adjusting the hydraulic lifters ie with spring pressure on the push rods thus hanging the valves open you would not be able to spin the push rods with your fingers.
               
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              • oldkimmer

                oldkimmer FABO Gold Member FABO Gold Member

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                Spinning the push rod can work for a solid lifter but not for a hydro lifter. Kim
                 
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                • 512Stroker

                  512Stroker We are all here because we are not all there.

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                  OP stated he was running a hydraulic cam.
                   
                • oldkimmer

                  oldkimmer FABO Gold Member FABO Gold Member

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                  Yes I know. U mentioned spinning the p/r which doesn’t work with a hydro cam. Kim
                   
                • RustyRatRod

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

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                  There's no way in the world hes right about that.
                   
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                  • 512Stroker

                    512Stroker We are all here because we are not all there.

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                    Exactly, you can only spin the push rods at zero preload which he would never have if the valves are hung up from too long of push rods.
                    I think we are all in agreement.
                     
                  • fishmens67

                    fishmens67 FABO Gold Member FABO Gold Member

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                    It does if you're following the procedure correctly. It doesn't take much preload.
                     
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                    • Sabremech

                      Sabremech Member

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                      This sounds quite easy and makes the most sense. I did use the EO/ IC method and that’s where I think things may have gone south. Pushrods are not too long nor did the valves touch the pistons. It’s not that hot of a cam. Hydraulic lifters we’re not pumped up or filled per Comp Cams instructions. Valves have been adjusted per RustyRatRod method and appear to be fine now. I’ve built a number of engines over my time and this has been a new one for me. Still not sure why the adjustment allowed for the valves to be open just enough to not build compression before. Engine is producing compression and will plan to fire it in the next couple of weeks when I can get back to it. Thanks to those who provided good information.
                       
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                      • 512Stroker

                        512Stroker We are all here because we are not all there.

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                        Cool, we need pic's.
                        A picture speaks a thousand words, video's are even better
                         
                      • gtgto

                        gtgto FABO Gold Member FABO Gold Member

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                        What was the length of the pushrods you used? Are you using 273 type adjustable rockers?
                         
                        Last edited: Jul 14, 2021
                      • oldkimmer

                        oldkimmer FABO Gold Member FABO Gold Member

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                        Without the lifters pumped up u can spin the p/r till u bottom out the lifter. This is what he did. U have to jiggle the p/r up and down which he obviously didn’t do. Kim
                         
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                        • fishmens67

                          fishmens67 FABO Gold Member FABO Gold Member

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                          How can valves be properly adjusted if the lifter isn't pumped up.
                          Rhoads lifters are required to be pumped up before installation.
                          makes me wonder if not pumping Comp lifters up as per Comps instructions is reason for so many Comp lifter failures.
                           
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                          • oldkimmer

                            oldkimmer FABO Gold Member FABO Gold Member

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                            Exactly, He said he didn’t pump them up even though the instructions said to. Kim
                             
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                            • fishmens67

                              fishmens67 FABO Gold Member FABO Gold Member

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                              I read the Comp instructions, it states there is no need to pump the lifters up.:realcrazy:
                               
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                              • MOPAROFFICIAL

                                MOPAROFFICIAL FABO Gold Member FABO Gold Member

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                                I like to adjust them with the intake off and see a good .040-.060 depression of the unpumped lifter cup.

                                There is an idea of .060 from the lifter cup bottoming out some do.. but that's a different set of springs
                                 
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                                • oldkimmer

                                  oldkimmer FABO Gold Member FABO Gold Member

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                                  Ok, it if u have adj rockers it is a good idea when ur only learning. Kim
                                   
                                • Bewy

                                  Bewy Well-Known Member

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                                  As noted in the Mopar Performance Book. The 4 position/180* method is suitable for adjusting lash for cams up to 290@050 duration. Longer than 290 requires the 8 position/90* method.
                                   
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