Measuring pushrods

Small Block Mopar Engine

  1. RAMCTD2003

    RAMCTD2003 340dart

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    I am a bit confused on the correct way to measure for custom pushrods.
    I have a 95 magnum block that has the cylinder head oiling hole already there so I am running LA Edelbrock heads that were set up and ported by Mike at MRL.
    I'm running the Hughes shaft mount 1.6 roller rockers. The cam is a custom roller grind that Mike uses on his builds. I am using stock Melling roller lifters as suggested by Mike.
    My problem is how do I measure for pushrods?

    I have #1 cylinder at TDC on compression stroke. The lifters are on the base circle of the cam. I have a checking pushrod and when I lengthen it out to where there is a little drag on it I locked down the adjuster and turned the motor over. The pattern on the valve stem is perfectly in the center. My pushrod length checker measures 6.58" overall and the cup depth on the checker is .150. Does this seem like the right way to measure?
    It seems like that length is pretty short.

    Thanks for listening.
     
  2. RustyRatRod

    RustyRatRod Bla de blizhibliz de blatde blizi bla bla FABO Gold Member

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    I always adjust so there is zero drag, but that's personal preference and will probably not make a hill of beans difference with what you are doing. Sounds like you are right on the money.
     
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    • RAMCTD2003

      RAMCTD2003 340dart

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      Thanks, I appreciate the response.
       
    • 71Scamper

      71Scamper Mopar runs thru my veins!

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      If you are running hydraulic lifters/non-adjustable rockers, you need to preload them by adding a quarter to half turn on the adjuster. Otherwise your valve train will be noisy. If your running adjustable rockers, turn the rocker adjustment so approximately 2 threads hang out the bottom and adjust the pushrod to zero lash. Then take your measurement
       
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      • RAMCTD2003

        RAMCTD2003 340dart

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        Thanks! I have adjustable rockers and what you describe is how I did it.
         
      • moper

        moper FABO Gold Member FABO Gold Member

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        Is it a hydraulic roller cam or solid? Reason being you do not need to add length for preload on the solid roller - you do for the hydarulic. Yes, Mopar small blocks with roller lifters have terrible pushrod angles and are very short...lol.
        I set the rocker where I want it (about 1 thread showing out the bottom), then set the checking pushrod to just where I can see the punger start to move away from the clip, then add .030. that's my pushrod length.
         
      • RAMCTD2003

        RAMCTD2003 340dart

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        It's a hydraulic roller. I will double check my measurement.
        Thanks for the advice.
         
      • mopowers

        mopowers Well-Known Member

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        Check both sides as well
         
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        • crackedback

          crackedback FABO Gold Member FABO Gold Member

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          Are the pushrod holes in your heads clearanced?

          If the heads are the LA head, you are likely going to have to clearance the heads.
           
        • RAMCTD2003

          RAMCTD2003 340dart

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          Yes they are. Mike at MRL took care of it for me.
           
        • moper

          moper FABO Gold Member FABO Gold Member

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          I forgot that... Unless the block was square decked you should check all four corners.
           
        • RAMCTD2003

          RAMCTD2003 340dart

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          It was square decked, but I will check so I know for sure.
           
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          • krazykuda

            krazykuda Well-Known Member FABO Gold Member How-To Section Editor

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            When I measured the pushrods for dad's Hemi, I put the test pushrod in each position and adjusted it to proper length 5 times per hole. Then take the average of the 40 intake and 40 exhaust measurements to get a good length.
             
          • RAMCTD2003

            RAMCTD2003 340dart

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            Thanks for the help earlier. I have another question. I ordered them and installed them. Fit great. My question is since I added the .030 do I need to add any more preload or is the .030 the preload?
             
          • 1qwikScamp

            1qwikScamp Well-Known Member

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            Generally you will set them while on the base of the can lobe. Turn the pushrod and tighten the adjuster until you feel some tention while turning the push rod then turn the adjuster 1- 1 1/4 turns. That is usually about .030 I had the same exact set up in my engine all Hughes stuff
             
          • mopowers

            mopowers Well-Known Member

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            On a 20 thread per inch thread pitch adjuster, a half turn is .025". That's what I've used in the past; although every lifter manufacturer tends to have a recommended preload range for their lifter.
             
          • T56MaxTorq

            T56MaxTorq Well-Known Member

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            You should also use a "checking" lifter which you can adjudt to the preloaded lifter height for your lifters. Then roll the engine over and check rocker valve wipe pattern and to set the pushrod length. This is the best way to set rocker adjustment to achieve the max valve lift. If you have the rocker adjuster set goofy and measure for a pushrod with lifter preload, the valves may not open as far as you think they are. Plus the wipe pattern may be off and could trash the guides over time. Hughes engines has a good write up on doin this. And you should! You paid good money for your engine. The more accurate and consistent your valve timing is means power and longevity.
             
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