lifter preload w/adjustable rockers

Small Block Mopar Engine

  1. dart_68

    dart_68 Well-Known Member

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    I've been doing some research into this and can't quite find the answer I'm looking for. I have stock 273 adjustable rockers and I wonder how far to turn them after 0 lash to get the proper lifter preload. I've seen anywhere from 1/4 to 1 1/2 turns. Which is it or what's the best way to measure for preload?

    360 LA with Oregon Cams hydraulic roller cam with stock hydraulic roller lifters. Gross lift is .539 int & .558 exh, 235/247 duration @ .050".

    Thanks!
     
  2. RammerJammer75

    RammerJammer75 Well-Known Member

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    Is this a street engine? If so, I'd go 1/2 or 3/4 turn. That's right where I run mine.
     
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    • toolmanmike

      toolmanmike FABO MODERATOR Staff Member FABO Gold Member

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      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

      What he said! I don't know what that is in thousand's of an inch but it's a hydraulic lifter. You need some but not too much. Chevy's always did 1/2-3/4 turn and I bet they had fine thread like Mopar did. If they clatter at 1/2, give them a little more.
       
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      • RammerJammer75

        RammerJammer75 Well-Known Member

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        I think it's close to .030 or .040"
         
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        • RustyRatRod

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

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          Nope. Hydraulic rollers work best with 1.5 to 2 turns down. They like a lot of preload.
           
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          • toolmanmike

            toolmanmike FABO MODERATOR Staff Member FABO Gold Member

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            Damn you would have to throw that "hydraulic roller" business in there. We read through the post too quick trying to beat you with an answer. We both knew you were lurking in the shadows ready to pounce. :poke::poke::rofl:
             
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            • RammerJammer75

              RammerJammer75 Well-Known Member

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              That seems like a ton of preload to me. I've only built one roller engine, but I set it at 3/4 and it was quiet as a church mouse. Interesting though.
               
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              • RustyRatRod

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

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                Roller profiles are such that they try to "throw" the lifter when the ramp comes around. By reducing the amount the plunger can travel, you counteract that inertia.
                 
              • RammerJammer75

                RammerJammer75 Well-Known Member

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                It makes sense to keep the lifter from bouncing on the cam lobe. Learn something new everyday.
                 
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                • RustyRatRod

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

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                  I always follow what the lifter maker says.....BUT the general consensus is that hydraulic rollers benefit from heavier preload.
                   
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                  • RammerJammer75

                    RammerJammer75 Well-Known Member

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                    The lifters in the roller engine I build said 1/2-1 1/4 turn preload, so I put 3/4 in it.

                    OP has stock lifters, so I'm imaging the heavier preload may be the way to go.
                     
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                    • RammerJammer75

                      RammerJammer75 Well-Known Member

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                      So you're using stock lifters with this camshaft? Just curious, but why? I would think stock lifters wouldn't be too happy with this camshaft.
                       
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                      • dart_68

                        dart_68 Well-Known Member

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                        Thanks for the replies. I too have read that hydraulic rollers like more preload. Oregon Cams said the stock lifters would be fine but I could upgrade to more race type hydraulic lifter but pretty expensive. This is a motor that I intend to race but I have to keep it relatively streetable to drive to the track. Plus the occasional get together.
                         
                      • mopowers

                        mopowers Well-Known Member

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                        As long as the oil groove on the lifter isn't exposed at peak lift, the stock lifters should be fine. Here are a couple cams folks on this site are running with stock replacement roller lifters. Maybe they'll chime in.

                        20151223_094123-jpg.jpg

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                        • AJ/FormS

                          AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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                          My thinking;
                          I currently have a little smaller cam, a Hughes HE3038AL,which is an HFT, and with 1.6 Mopar arms, .549/.571 lift 230/237/110@.050.; and with their HD circlipped lifters.
                          I run the lifters on the edge of ticking, so they are pretty much fully pumped up. That way, even if the valves float a bit, as long as there is enough built-in valve to piston clearance,the engine won't go down.
                          I think the idea is working, cuz I've been revving this thing to 7200 since 1999.
                          Your results may vary.
                          I once missed third gear and saw the tach needle swinging across 8000....... on it's way back down.... After that I bought a rev-limiter..... and fixed the dang shifter. The engine idled just fine..... and no, I never tested it again,lol.
                          I see;
                          a pretty heavy 12* split there; can I ask what the thinking is on that?
                           
                        • dart_68

                          dart_68 Well-Known Member

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                          I went with what Oregon Cams recommended. They recommended 2 cams and I chose the smaller of the 2 because we thought it would better fit my needs. Why such a split...I don't know.
                           
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                          • raymond

                            raymond Well-Known Member

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                            I run a bullet hyd / roller they told me to run little or NO preload , it was a little noisy so now I run around a third of a turn,



                             
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                            • dart_68

                              dart_68 Well-Known Member

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                              The cam I got is also a billet. Had to get a diff dist. drive gear.
                               
                            • TT5.9mag

                              TT5.9mag Two atmospheres are better than one

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                              There is some math you can do with the thread pitch of the adjuster to figure out how many turns equals the preload you want. That cam isn’t what I would call wild so the stock lifters will be fine as long as the oil band isn’t exposed. I run mine at 040 preload and it’s quiet. It’s a magnum though.
                               
                              Last edited: Nov 23, 2020 at 12:25 PM
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                              • AJ/FormS

                                AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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                                I think those adjusters are 28 threads per inch, so every turn would be 1/28 inch or .036
                                 
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                                • MOPAROFFICIAL

                                  MOPAROFFICIAL FABO Gold Member FABO Gold Member

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                                  I tighten them till they're quiet.
                                   
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