Roller Valve Spring vs FT Valve Spring

Small Block Mopar Engine

  1. Jadaharabi

    Jadaharabi FABO Gold Member FABO Gold Member

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    My question is.
    Will the valve springs on my heads that are 125 on the seat and 300 lb at .550 lift with a FT cam work with a roller cam with .480 lift?
    What is the difference between a roller cam valve spring and a flat tappet valve spring?
     
  2. yellow rose

    yellow rose Master Of Insanity

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    The spring rate is usually less with a SFT spring and with that little on the seat and .480 lift you’ll have nothing over the nose.

    That might be a bit sketchy at a pretty low RPM.

    Just my .02
     
  3. PRH

    PRH Well-Known Member

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    Solid or hyd roller?
     
  4. Jadaharabi

    Jadaharabi FABO Gold Member FABO Gold Member

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    Hydraulic
     
  5. PRH

    PRH Well-Known Member

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    The main issue is..... the hyd roller lifters are pretty heavy, especially the retrofit style, so it takes more load to keep everything in control.

    So, 125/280-ish will work up to some rpm point with a hyd roller cam, but unless the cam profile is rather tame...... there’s a good chance the valvetrain will start to get unhappy at a fairly modest rpm(low-5000’s).
    Where it actually happens will be mostly dependent on the cam profile.
     
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    • yellow rose

      yellow rose Master Of Insanity

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      Well that’s a bit different. That’s not that low.
       
    • Jadaharabi

      Jadaharabi FABO Gold Member FABO Gold Member

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      I'm wanting to put the roller in a 1990 roller motor. It will have 1.5 factory rockers and ported heads with edelbrock alum head valve springs(1.80? Installed height)

      HR-286d-SBM Short Snout Magnum

      Advertised Duration
      In. 286
      Ex. 298

      Duration @ .050
      In. .227
      Ex. .234

      Valve Lift 1.6
      In. .512
      Ex. .512

      Lobe Lift
      In. .320
      Ex. .320

      LSA
      112

      It's a Texas regrind.
       
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      • Garrett Ellison

        Garrett Ellison Amateur driver on public roadway, do not imitate.. FABO Gold Member

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        Is that with the P/N 5767 springs, 9736 retainers, and 9611 locks? What type or diameter are the valve seals?
         
      • Jadaharabi

        Jadaharabi FABO Gold Member FABO Gold Member

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        If that is what Edelbrock used that would be them. I think the seals are .530 or something like that Teflon?
         
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        • PRH

          PRH Well-Known Member

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          At a minimum, I’d shim the springs up to achieve 135-140lbs on the seat.
           
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          • 318willrun

            318willrun Utube channel 318willrun

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            Usually roller cams have more spring pressure than a FT when comparing equivalent lifts/duration.
             
          • Garrett Ellison

            Garrett Ellison Amateur driver on public roadway, do not imitate.. FABO Gold Member

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            Do you know the inner spring seat height (the one with the .755 diameter) of the retainers? If you can come up with that, I can find out what a set of Melling VS-2203 springs (.745 I.D. .900 O.D. & 1.77 free length) or equivalent added as an inner spring would add to your seat and open pressures and what locator it would need to shim it up with. The downside is it’s about a $100 upgrade, and there’s possibly a set of springs available for less than that. But a different set of springs is probably going to require a different set of retainers, so it still may be the lowest cost option. Shimming would be the lowest cost option, by far.
             
            Last edited: Aug 11, 2020
          • furrystump

            furrystump Well-Known Member

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            The stock eddy valve springs were just on the edge of being adequate for the advertised limit to begin with, not a big safety margin.
             
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            • flyfish

              flyfish C8H18+N2O = :-D

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              Roller cams need more seat pressure than solid flat tappets....they need more spring pressure overall to control the weight, but in this particular case more seat pressure at a minimum. Main thing with rollers is you don't want them to bounce...and they are quite heavy, which is why they need more spring to control things.
               
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              • MOPAROFFICIAL

                MOPAROFFICIAL FABO Gold Member FABO Gold Member

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                Last lunati hyd roller I set up was 135 lbs @seat.
                 
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                • Jadaharabi

                  Jadaharabi FABO Gold Member FABO Gold Member

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                  What would be a good single spring with damper that I could put on these heads with my roller cam?
                   
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                  • Garrett Ellison

                    Garrett Ellison Amateur driver on public roadway, do not imitate.. FABO Gold Member

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                    I'm looking for the inner step diameter of the 9736 retainers, and I will go from there with Mr. Wallace's spring calculator. Do your valve springs have a damper? We also need to confirm beyond a doubt those are the P/N's for the components.
                     
                  • Jadaharabi

                    Jadaharabi FABO Gold Member FABO Gold Member

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                    They are just a spring and damper. There is no innerspring.
                    I'll have to check on what the spring number is cuz I don't know off the top of my head.
                     
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                    • Garrett Ellison

                      Garrett Ellison Amateur driver on public roadway, do not imitate.. FABO Gold Member

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                      Okay, I apologize, I misread your question and I caught where you ad said OTB magnum heads. My :realcrazy: Bad! I will get back to you once I get all the figures together from the Edelbrock spec sheet.
                       
                    • Jadaharabi

                      Jadaharabi FABO Gold Member FABO Gold Member

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                      Never said magnum heads. Said la roller motor. It has 308 heads. I want to put in a bigger cam.
                       
                    • Garrett Ellison

                      Garrett Ellison Amateur driver on public roadway, do not imitate.. FABO Gold Member

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                    • Jadaharabi

                      Jadaharabi FABO Gold Member FABO Gold Member

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                      • Garrett Ellison

                        Garrett Ellison Amateur driver on public roadway, do not imitate.. FABO Gold Member

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                        Okay, I got you! The item we need to confirm is the Edelbrock 9736 retainers. If that's the case, you can go with a set of 5845 Edelbrock valve springs. These were what Edelbrock ran on the hydraulic roller version of these heads with the 9736 retainers with 150 closed at 1.800 installed height, 420 open at .580 open.
                        Edelbrock Sure Seat Valve Springs 5845
                        https://www.edelbrock.com/sure-seat-valve-springs-5845.htm
                        I'm looking over other options but it appears that Edelbrock went out of their way to design spring retainers for an outer spring inside diameter no one else manufactures.
                         
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                        • Krooser

                          Krooser Reform School Graduate

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                          Comp, Summit, Speedway and others sell a 1.460 spring...common size.
                           
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                          • Garrett Ellison

                            Garrett Ellison Amateur driver on public roadway, do not imitate.. FABO Gold Member

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                            That's true, but that 1.06 inch diameter on the retainer register is what bites you. Always good to have a valve spring positively located. I'm sure there's some allowance there, but I don't think that’s a good place for gambling! Now if you change retainers, you can do what you want, but the initial payout is exponentially higher.
                             
                            Last edited: Aug 17, 2020
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