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Pushrod length and rocker arm question

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by longbedder, Oct 27, 2006.

  1. longbedder

    longbedder 1/2 ton status Premium Member

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    I've got an engine that I am removing the Vortec heads from and replacing with some 041 heads (casting 3947041) that I had in the garage. This is to facilitate putting an EGR manifold on (which I also already have) and passing smog - please don't dog me for removing the vortecs.

    Anyway, two questions:
    1) Is the pushrod length the same between the old (pre-86) heads and the vortecs?

    2) Is there any reason I could not use the self-aligning rocker arms from the vortecs on the old heads? The studs are the same diameter, and they *appear* to line up properly.
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    I believe the length should stay the same, but I wouldn't bet on it. Need to check before assembly. Assuming they will be the right length is a bad idea when changing things around.

    No, you can't use the Vortec rockers. The valve stems are longer on the new heads to keep the "rails" of the new rockers on the valve. If you use the Vortec rockers on a non-self aligning valve setup, the rails can push the spring retainer down and potentially lose the locks.
     
  3. longbedder

    longbedder 1/2 ton status Premium Member

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    That makes sense on the rockers, and I was going to assume you could not interchange them.
    Anybody have any straight pre-86 pushrods laying around that they could measure the length on? If not I'll hae to swing by the junkyard...
     
  4. longbedder

    longbedder 1/2 ton status Premium Member

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    Nevermind...after some Googling, I'll custom-length check 'em.
     
  5. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Aren't the vortec engines a roller engine? If so then the pushrods will be shorter than the non-roller engines but if neither engine is roller cam then they will be the same length. The rockers should not be used but not for what Dorian said, the valve tip lengths are the same as earlier valves but the self aligning rockers would be fighting against the guided holes in the early heads.
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    You don't see any potential problems between this:
    [​IMG]

    and this?

    [​IMG]
     
  7. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Nope, the only problem i see is the engine on the bottom needs to be better taken care of.
     

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