Rocker arms for 408 build

Small Block Mopar Engine

  1. Idaho

    Idaho Well-Known Member

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    Thanks Rob. Read all that a while back, been in contact with Mike.
    No answers to be had for Magnum heads.
    I spoke to PRW today, they minimize any concern about weakness without a girdle with my setup at about 300 lb open. Also found they likely to not fit under standard valve covers.
    I have seen a report that the HS setup great with no shims on an RHS head so perhaps the lack of fulcrum height adjustability is a non issue, stronger, more stable.
    One irritant, I see no reasonably priced tall valve covers for a magnum so I lean toward the nonadjustable HS.
     
  2. rumblefish360

    rumblefish360 So close, yet so far away FABO Gold Member

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    Then use regular LA covers on the Magnum.
    But I’d like to score a set of the black wrinkle MP “MAGNUM” covers myself!
     
  3. Idaho

    Idaho Well-Known Member

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    I did not know that was possible. Google shows it works. Thanks.
    Still debating which rockers.
     
    Last edited: Jun 2, 2020
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    • fishy68

      fishy68 Tyr Fryr's Inc. FABO Gold Member

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      Idaho, I have EQ magnum heads on my 408 and am using the HS rockers but the adjustable ones. Geometry was very close. I wouldn't say perfect but close. Just thought I'd let you know my experience with them
       
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      • Idaho

        Idaho Well-Known Member

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        Thanks for that. I'm not sure if it was you who posted that experience before. If not that makes two.
        I do like their design.
        What valve covers are you using?
         
      • Wyrmrider

        Wyrmrider FABO Gold Member FABO Gold Member

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        525v lift stock rockers work fine
         
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        • moparallen

          moparallen Moparhead

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          I will be glad to share my experience.
          1 thing. I was using stock magnum heads. We cut the seats for 1.97 RT valves and I had Hughes .500 lift Single springs with 2.2 retainers. I was using a Hughes custom hydraulic cam with a .300 base circle. When all said and done I was at about .480 lift. I was racing oval dirt 1/4 mile where the rules said factory only on the valve train except screw in studs and guide plates were allowed. I used 3/8 MP fulcrums that I cut 1/2 the platform off with a hi speed cutting wheel on a die grinder. I used the 5/16 x 3 8 studs from the Comp Cams kit along with the guide plates. I used the MP push-rods made for the conversion. (7.165 I think was the length)? I also had to take some material off the stud close to the bottom because the fulcrum would go down to far and get tight. I then used Stock rockers with poly locks and the the adjustment was 1/2 turn from zero lash. I ran this set up for 15-20 race nights at 6500 RPM lap after lap. I broke a fulcrum in half but never noticed a running difference. We found it doing a manifold swap when the rules changed for the next year..
          The along with "any factory" manifold rule change it was also changed that "stock style" rockers could be used. I then went to a custom length hardened push-rod and the Summit Brand 1.6 Chevy rocker. At that time I began to converse with Joey Case from Dallas GA. He advised me to run the lifters preloaded at .120 deep.
          I never had a geometry problem that was out of this world.
           
        • fishy68

          fishy68 Tyr Fryr's Inc. FABO Gold Member

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          Mopar Magnum aluminum
           
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          • Idaho

            Idaho Well-Known Member

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            That's some interesting stuff. I'm having trouble understanding how stock rockers are used with a non-stock fulcrum and poly locks.

            That had been my understanding. When I looked at what was happening with .515 lift I did not like the look. With that and my .020 variability in valve height I decided to bite the bullet and order adjustable HS rockers.
            If nothing else I will have peace of mind. If I had not done the stroker, I think I'd have tried the stock rockers. Too much invested now.
             
          • moparallen

            moparallen Moparhead

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            Last edited: Jun 8, 2020
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            • Krooser

              Krooser Reform School Graduate

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              Stock rockers are fine. All those old super stocks in the 60's ran the hell outta them. You won't have any issues.
               
            • Idaho

              Idaho Well-Known Member

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              No pedestals in the 60s right?
              I think you are referring to the LA style shaft rockers.
               
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