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School me on EGR's

Discussion in 'The Garage' started by NoReGrEtS, Nov 5, 2006.

  1. NoReGrEtS

    NoReGrEtS 1/2 ton status

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    why does the manifold have the egr hole's in the bottom but no hole in the head?

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    Last edited: Nov 6, 2006
  2. JohnDeere

    JohnDeere 1/2 ton status

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    I may be wrong but i think it circulates through the hole manifold.
     
  3. NoReGrEtS

    NoReGrEtS 1/2 ton status

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  4. vortec

    vortec 1/2 ton status

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    on both my old engine and new (reman), the heads had no apparent provision for egr plumbing, they looked exactly as yours do. my inspection readings did not indicate a problem with the egr system, so it appears to function, somehow, that way. i'm curious about this, too.
     
  5. longbedder

    longbedder 1/2 ton status Premium Member

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    Because those are non-EGR heads. The EGR system will not function like that.
     
  6. NoReGrEtS

    NoReGrEtS 1/2 ton status

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    I was thinking that, but I didnt know if the intake gasket would have slots and pulled it from the heat cross over, then thought the slots and into the egr valve its self. if that makes sense.

    I was thinking that some one may have pulled the heads and put some thing else on. I'm going to have to check the casting numbers on the heads. witch would explain why the cam was bad(my have swap the lifters around).

    Any one else know any thing about this?



    Thanks Shawn
     
  7. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    The hole in the center of the head is the exhaust crossover hole and when it enters the intake manifold it is routed all through the intake and the holes you see next to each other simply allow the EGR valve to move exhaust from one part of the manifold to the opposite hole and back into the plenum side of the intake.
     
  8. longbedder

    longbedder 1/2 ton status Premium Member

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    Yeah, someone most likely swapped those heads on there. A less-likely occurrence is that someone may have swapped an EGR manifold onto a non-EGR vehicle. Do you know which your vehicle is supposed to be (by the year/model or underhood sticker)?

    Anyway, you can jury rig the manifold to get the EGR to function. It involves drilling and installing some plumbing. The plumbing can reside inside the lifter valley.

    Drill into the manifold EGR passage nearest the front of the vehicle.
    Drill into the exhaust crossover.
    Install tubing between these two holes, and seal it up good. Welding is best, but some other high-temp oil-resistant stuff may work (JB weld or something).

    Repeat the steps as above, but between the rear-most EGR passage and the intake plenum.

    This will work, as exhaust gases will be metered by the EGR valve from the exhaust crossover to the intake plenum. Be sure and use ported vacuum to operate the EGR (not manifold vacuum).

    Beware of the fact that this tube setup is not optimal, as the tubes will tend to clog over time. It should get you through the smog check, though.
     
  9. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    There is no difference in the heads from 1955-1995 except port size. Every GM head made from 1955-1995 only have the center exhaust crossover hole and nothing else.
     

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