Help with Valvesprings and valve float. Noob

Small Block Mopar Engine

  1. flyfish

    flyfish C8H18+N2O = :-D

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    I thought you were worried about spending money on rockers??....goes out and buys a solid roller, lol.

    Just a FYI, you CANNOT go cheap with the rockers on a solid roller setup. The spring pressure necessary to pull those heavy lifters back down would destroy a cheap rocker in seconds. I ran a small street solid roller a few years back, and even that had pretty hefty springs (185# seat and 465# open). Typical roller springs are in the ~250# seat, and ~600# open.

    I would get a set of Comp Pro Mag rockers and be done with it....they can take just about any abuse you can throw at them. COMP Cams Pro Magnum Shaft Mount Roller Rocker Arms 1622-16
     
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    • 340Duster247

      340Duster247 Well-Known Member

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      I had money set aside for the car because I was gonna change some other things. Now I've made the decision to spend the money on what we have spoken about in this thread.
      I'm actually looking into the 1622s right now. In stock at local parts shop. What's the deal with hold down hardare when it comes to these since it's not included. Can I used the hold downs from my prw kit?
       
    • flyfish

      flyfish C8H18+N2O = :-D

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      Not sure on the hold downs. The set I have on my car I bought YEARS ago (early 2000's). They were before they installed the bronze bushing to make them indestructible. Might want to check on other part numbers, maybe they will have it complete....not sure why it says it doesn't have hold down hardware.
       
    • nm9stheham

      nm9stheham Well-Known Member

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      FWIW.... I am pretty sure the OP has the PRW PQ rockers. The needles are short length needle bearing assemblies, 1 pressed into each side. So you take them out and you have a recess in each side, with a smaller ID 'step' in between. So you have to bush them with 2 short bushings about .375" long on each side. Or machine that step out in the inside... not worth it IMHO unless you already own a mill. Probably not what most think of when they think re-bushing.... as with one long single bushing.

      (I'm gonna re-bush my PQ's with 2 bushings per rocker, but I won't put them in harsh use. I expect to make a jig for them to make sure the 2 bushing are exactly aligned.)

      IMHO, the OP is better off with the PRW steel rockers as has been suggested. He has other things to worry about.... (If he does have them rebushed like I described with 2 bushings, I'll suggest some Sleeve Retaining compound in each bushing's bore. The bore ID's vary a bit....)
       
    • nm9stheham

      nm9stheham Well-Known Member

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      Yes.. you are putting heavier lifters in there now and so things are going to be even more challenging to keep under control. 1.5 rocker ratio will help some.
       
    • Cudafever

      Cudafever Well-Known Member

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      I have never owned a mechanic Roller cam
      But i thought the lifter was lighter then the Hyd roller...?
       
    • yellow rose

      yellow rose Doctor of Thinkology.

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      I think you are correct in that if you knock the bearings out, you need to press in two bushings. That's why I said to get ahold of Mike because I thought he posted once that he made up the fixtures to put bushings in those rockers. I know there are some rockers he can convert to cup adjusters too.
       
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      • nm9stheham

        nm9stheham Well-Known Member

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        The OP is thinking of going from hyd flat to mech roller. Hence the weight increase.....
         
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        • Wyrmrider

          Wyrmrider Well-Known Member

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          lifter weight is not the big deal that valve and retainer weight is
          use lightweight tool steel retainers TI anr not worth the $$$ here
          Beehive springs would make more difference than lifters
          if getting new valves use chevy valves and proper valve guide inserts
           
        • gzig5

          gzig5 Well-Known Member

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          If you were to go with two bushings pressed in, the correct way to do it would be to ream them to size after pressing in. That assures alignment and sizing. I don't know that I would bother with a bearing length that short. If you can't bore them yourself or pay someone to do it to do a one piece full length bushing, I'd sell them as is and put the money towards something better. Just not enough bearing length to support anything but a very mild spring, IMO.
           
        • yellow rose

          yellow rose Doctor of Thinkology.

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          I'm not sure about that. I've run unbushed aluminum rockers with 320 on the seat and over 800 over the nose and shifted at 8500 plus and never had an issue.

          If the oil timing to the rockers is correct, they don't need a ton of bearing area. Getting the oil timing to the rockers correct is a whole 'nother issue and discussion.
           
        • gzig5

          gzig5 Well-Known Member

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          Sure, but they were supported the full width of the rocker, right? take the bearing out of the OPs rockers and replace with same width bronze and you get maybe 1/2 to 1/3 the surface area. No way you will maintain an oil film with that small of an area with any kind of spring pressure. If you could, they would be doing that on race engines. Bearing width = friction and friction robs HP.
           
        • yellow rose

          yellow rose Doctor of Thinkology.

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          I'm getting lost here. If you just replace the bearings with bushings, you still have the same bearing area. Doesn't matter if it's bronze or aluminum. Think about the exhaust rocker. It has the same spring loads as the intake (talking W2-5 stuff here since I'm using my example) yet the exhausts show no more wear than the intakes with ~ 65% of the bearing area of the intake rocker.

          My point is there is plenty of bearing area there. Push some bushings in where the bearings were and go. It will be fine.
           
        • PRH

          PRH Well-Known Member

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          As your own testing has proven....... they’re good for about 5600rpm with that cam and those rockers.


          Without completely revamping the entire valvetrain, as you’re now planning to do, what were his suggestions for getting the motor to rev beyond that point?
           
        • gzig5

          gzig5 Well-Known Member

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          I disagree with there being enough area for a plain bearing if you only replace the roller element. Roller bearings have different load carrying capacity than a plain bearing for a given width. The plain bearing relies on a fluid film to be maintained and the area of that film determines the load. I'm not on top of the math behind it but from working with machinery I guarantee you that if you have a 1" wide roller or ball bearing, you will need at least a 2" or more wide plain bearing to replace it. Bearing surface velocity and other load factors affect it too. The bearing width on a stock 273 rocker is what, 1 1/4 - 1 1/2" wide and they still wear the shafts out over time with stock springs. Bottom line is I would not rely on a 1/4" wide plain bearing on either end of a rocker to live a long time in a high performance motor.
           
        • yellow rose

          yellow rose Doctor of Thinkology.

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          I'd have to go pull you PRW rockers, but I'm pretty sure it's two .250 wide bushings supporting all the load. That's all it takes, again, if the oil timing is correct so there is pressurized oil there.

          Making it way too hard for the OP. Hell, he can put aluminum in where the bearings were and it will live forever. It ain't that hard. He isn't spinning the guts out of it, or running spring pressures like a race engine.
           
        • gzig5

          gzig5 Well-Known Member

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          Agreed, getting a little OT and not helping the OP. I have a new set of SS PRW with bronze bushings on my desk and can take measurements when I get home and close that aspect out.
           
        • nm9stheham

          nm9stheham Well-Known Member

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          If putting bushings in each side of these PQ rockers, you get right around 62% of the overall rocker width as surface area... right at 0.75" total bushing length (.375" bushing per side) per rocker in a 1.2" wide rocker body. (An SBM rod bearing is just over .8" wide BTW.) Plus the inner bore on these rockers is a larger ID than the shaft and the oil enters there and forms a reservoir of oil in there. So it'll probably do better than you are fearing; the saving grace of a sleeve bearing of any type in this application is that the speeds are very low..... just a small fraction of the speed seen at the rod and main bearings.

          Yes, it makes more sense to put in a full bushing (which is doubtless a driver to using a full bushing), but that is just too much machining on these to make sense (to me). And the bushings will have 50-100 times better bearing area than those teenie-tiny 1/4" long needles spaced far apart. These are not set up side by side like you normally see in a U-joint cup, but are spaced widely. I looked them up, and those needle bearing assemblies were designed for a completely different application than this high, oscillating load. The 'designers' (and I use that term quite loosely!) just saw a cheap part and said "Those will work for those stupid Americans!"
           
        • Wyrmrider

          Wyrmrider Well-Known Member

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          YR knows cam oil timing, posted on it several times
          al galls much easier that bronze I would not use 1/4 inch al instead of 1/4 bronze
          when the intake cocks it's only riding on the outside anyway
          I mentioned earlier the only way to make needles direct on shaft work
          chrome moly heat treated shafts are more money than new rockers
          (for that High end build)
           
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