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Valve adjustment on SBC

Discussion in 'Shop - Engine' started by Project1500, Aug 17, 2005.

  1. Project1500

    Project1500 Member

    Joined:
    Feb 24, 2003
    Location:
    So cal
    Im doing a valve adjustment on a newer Chevy with a 350 in it and ran into a problem (I think). Its a roller cam w/ hydraulic roller lifters.

    I did the adjustment like you normally would. Move the pushrod around until there is zero lash. Then tighten the nut on top of the rocker 360 degrees and they are set. On most of them when I did the 360 degree turn on the nut the spring in the lifter would compress like normal (and still can compress for a few more thousandths until the valve moves) and the valve would stay put. On a couple of them when I would tighten them the 360 degrees the actual valve would compress and not the spring in the lifter. Is this bad? Why is this?

    I made sure I'm adjusting the valves when the lifters are not on a lobe of the cam. I can visually tell the lifters are all the way down because the lower intake manifold is off. On every lifter the springs are completly extended and none are stuck down.

    Im re-using the old cam, lifters, pushrods since they are in good shape. I cleaned the lifters though and I think when I did this I cleaned the oil out of some. I think the ones that are still filled with oil wont allow the springs in the lifter to compress which is not a big deal once the engine is running? right?

    Im confused some can any help?
     
  2. Kbach66

    Kbach66 Member

    Joined:
    May 9, 2002
    Location:
    Simi Valley, CA
    I don't know what you mean by "newer" 350....but back in the old days I remember adjusting valves on a hyd. cam (non roller though) like you describe, but only 1/8 - 1/4 turn after 'zero lash'.
     
  3. PBR

    PBR Well-Known Member

    Joined:
    Apr 6, 2001
    Location:
    Culver City, CA
    i don't know if you are doing it in any particular order but here is how i have done it in the past.
    i don't think the roller rockers should make a difference on adjusting the valves as long as the lifters are hydrolic.

    get the motor at tdc on #1 cylinder (both #1 valves should be shut)

    adjust:
    #1 exhaust
    #1 intake
    #3 exhaust
    #5 intake
    #7 intake
    #2 intake
    #4 exhaust
    #8 exhaust

    now rotate engine 360 degrees (the mark on the balancer should go back to tdc on cyl #6)
    adjust:
    #3 intake
    #5 exhaust
    #7 exhaust
    #2 exhaust
    #4 intake
    #6 exhaust
    #6 intake
    #8 intake

    get the push rods to zero lash and go 3/4 or a turn clockwise
     
  4. Project1500

    Project1500 Member

    Joined:
    Feb 24, 2003
    Location:
    So cal
    Ya PBR thats the way I did it. My problem is though when I do the turn on some, the actual spring in the lifter compresses and on some the valve moves and the spring in the lifter doesnt compress. Why doesn't the spring in the lifter compress on some? This is causing the valve not to fully seat.

    Kbach I was just being specific. Basically the same thing just not flat tappet. Wasnt 100% sure if the newer trucks 1990+ required different adjustment procedure.
     
  5. scottm

    scottm Well-Known Member

    Joined:
    Feb 7, 2005
    Location:
    scottsdale AZ
    I always set hydraulic lash at 1/2 turn. But to be extra sure that the lifter isnt on a lobe, I follow the firing order, turning the crank 90° each time.
     
  6. PBR

    PBR Well-Known Member

    Joined:
    Apr 6, 2001
    Location:
    Culver City, CA
    i was just sure you were doing it right... maybe helton knows what the deal is... my guess would be bad/frozen lifters, but just a guess.
     
  7. Project1500

    Project1500 Member

    Joined:
    Feb 24, 2003
    Location:
    So cal
    Thats what I was thinking either there bad (frozen) or they are just full of oil and won't compress......
     
  8. matt_helton

    matt_helton Racer

    Joined:
    Feb 16, 2003
    Location:
    Yorba Linda, CA
    did it make lifter noise before? if not i wouldnt sweat it. once it fires up it "should" be ok. lol
     
  9. Project1500

    Project1500 Member

    Joined:
    Feb 24, 2003
    Location:
    So cal
    It didnt make any noise before. I had to take it apart for another reason.

    How many miles can you normally run on these type of lifters before they "should" be replaced?
     
  10. matt_helton

    matt_helton Racer

    Joined:
    Feb 16, 2003
    Location:
    Yorba Linda, CA
    i dont think there is any set mileage. id leave em untill they either go bad or you tear the motor down for some other reason and you just wanna replace em cus you are in there. its not like they are that expensive.
     

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