Rocker stud spacers

Discussion in 'Engine Topic' started by biker, Nov 4, 2019.

  1. biker

    biker Veteran Member

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    I'm looking to eliminate my guide plates as I already have self-guiding rocker arms. I don't want to replace the studs as they are all fairly new ARP studs, so I would just like to use machined washers/spacers that are the same thickness as my guide plates so I can retain the same height for the rocker studs.

    Is there a purpose-built washer or spacer for this application or should I just go with whatever decent 3/8 washers I can find.

    Thanks.
     
  2. jeff swisher

    jeff swisher Veteran Member

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    How about take the guide plates and cut them so they do not guide the pushrod.
    Probably just going to be removed and stored in a drawer until you give them away to someone needing them.
    That's what I would do.
    That way you know they are correct height. And most of them are joined as pairs and this may allow a bit more rigidity than a separate washer under the stud.
    Win Win.
     
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  3. biker

    biker Veteran Member

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    And this is why I ask... Thanks man, I did not consider that as an option. However, as you hinted at, I am a hoarder and love to hang on to stuff, but in this case cutting them up is the right thing to do for the peace of mind of knowing they are the right dimensions.

    While I have your attention, throw money considerations out the window for a moment and give me your opinion on a shaft mounted rocker system. I have a 550ish lift hydraulic roller cam and 1.5 stainless full roller rockers, so not really outrageous spring pressures and RPM doesn't go over 6200. Just wondering if there is any real advantage with rigidity as compared to the 3/8 studs I now have, or if the shaft system is able to better align the rocker tip over the valve stem tip.

    Any thoughts appreciated.
     
  4. djorgensen3

    djorgensen3 Veteran Member

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    You could change your studs out to 7/16" versions and upgrade the trunions on your rockers and be fine with no need for a shaft system which is super spendy. Or you could buy a stud girdle for your 3/8" rocker studs.
     
  5. biker

    biker Veteran Member

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    Very true. I also did not consider just changing the trunions to accommodate bigger studs. I'd like to avoid a stud girdle, and I'm wondering if there are other advantages to the shaft system such as rocker tip alignment or improved fulcrum point that might reduce the travel of the rocker tip across the valve stem. Bear with me...it's winter here and I now have time to overthink this stuff.
     
  6. jeff swisher

    jeff swisher Veteran Member

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    I do not care for the stud girdle ..That is a lot of stuff in the way in my mind.
    You are correct in the shaft system can have a smaller sweep than the factory SBC stud system.
    But that is when using 1.65 pivot length vs the SBC stock 1.4".

    If you are bucks up then go for the shaft system.
    Will you see gains in HP .. probably not anything you could really tell.
    At your level you are not really pushing the envelope.
    I use 7/16 studs when I go with a screw in stud.
    Why not.. most of the time if I am going with screw in studs I must be looking for more power and not using stock rockers.. About the same price for 3/8" studs and rockers as it is for 7/16".

    I ran 348 psi open pressure on solid flat tappet .571" lift with a 1.6 rocker 7/16 studs.. never an issue.
    This was on some HO 305 heads 1.94-1.60 valves. 252@ .050 106 LSA Lash was .026"
    Short shifted at 7000 rpm. That was some old 1.250 single springs with damper and steel retainers.

    I do not like those springs so much today..I run PAC beehives now and so far I really like them.
    Much less spring rate 313 vs the 400 rate.

    No idea what you have.
     
  7. muscl car

    muscl car Veteran Member Lifetime Gold Member

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    On my AFR cyl heads when I ordered them they were spec'd out with 7/16th studs


    20190611_145538.jpg
     
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  8. biker

    biker Veteran Member

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    Excellent Jeff, thanks for the wisdom. I wasn't so much concerned about gaining power as I was about just better reliability, less trauma on the valve guides from things lining up and working better. Shaft system looks like a bit of a better mouse trap in that regard.
    I can't remember my seat and open pressures, but the springs were just enough for what I needed for the hydraulic roller at my lift and rpm limits. No float, no bind.
     
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  9. biker

    biker Veteran Member

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    Ok good. Nice looking engine. Now I have air cleaner envy.
     
  10. G72Zed

    G72Zed Veteran Member

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    Good idea in removing those guide plates w/self aligning rockers.

    And as Jeff said, cut them and use them as the spacer. If not, you could use an ARP flat "head bolt" washer as they are very close to the same thickness as most guide plates in your case (.115-.130 +/-) and are the correct size, 7/16, your studs although 3/8 on top, are 7/16 NC in the head.

    Long cold winter with time, make sure the stud does not protrude to far into the intake port, you could do some trimming if need be.
     

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