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AIR manifold only has one port on each side

Discussion in 'The Garage' started by mccomas, Feb 12, 2004.

  1. mccomas

    mccomas 1/2 ton status

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    my AIR manifold only has one large port on each side. i have contacted several header manufactures and they are all telling me that their setups have 4 smaller ports down each side. my 86 does have a 95 GM crate motor.

    is the setup i have (shown below) common with my year or am i missing something?

    [​IMG]
     
  2. k20

    k20 3/4 ton status

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    my old 89 350 only had one. The big blocks I have seen w/ AIR(mine included) have 4 ports, but all of the sb's ive seen w/ air only have the one port. Talk to Thorley they have the headers you will need, good headers they are ones i have/had, but you will pay for the quality. Just so you know, you buy headers to fit the vehicle, not the engine.
     
  3. mechted

    mechted 1 ton status Premium Member

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    My '78 350 has 4 tubes... (may have something to do with California emissions though)

    i doubt that switching from 1 tube to 4 tubes would cause any problems (smog wise) just get more heater hose to re-plumb it
     
  4. k20

    k20 3/4 ton status

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    probably does have somethin to do w/ cali emissions not too many make it 'cross country lol.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    But the question really is whether that one tube up front uses a bigger fitting than the 4 tube setups or not.

    If it uses the same fitting size as the 4 tube setups, then any headers setup for 4 tube AIR will work, you'd just plug the other 3. Looks to me like his is bigger than the 4 tube fittings though.
     
  6. k20

    k20 3/4 ton status

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    well on my 496 the 4 ports are half the size of the single port that was on my 350
     
  7. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    They are bigger, I had one single air tube and I just figured that the smog headers would just have 4 tubes that come together and connect the the existing single hose. That is how it has to work because with manifolds all the cylinders are connected to where headers have a tube for each cylinder. With only one line, only one header tube would get air. /forums/images/graemlins/thinking.gif
     
  8. k20

    k20 3/4 ton status

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    my thorley smog headers only had 1 port for my 350. 4 on my 496.
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    Since AIR is never diverted to the catalytic converter in the trucks, I believe it "pumps" constantly, which is typically for cat converter operation, not the "post combustion combustion" that the AIR does, that is a cold engine function. So even with one AIR tube into one header tube, the catalytic converter will still see that, and the additonal air will be mixed before reaching the converter.

    Perhaps you could just put a 4 tube AIR manifold in place of the 1 tube though, as long as the upper hose is the same piece...
     
  10. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    [ QUOTE ]
    Since AIR is never diverted to the catalytic converter in the trucks, I believe it "pumps" constantly, which is typically for cat converter operation, not the "post combustion combustion" that the AIR does, that is a cold engine function. So even with one AIR tube into one header tube, the catalytic converter will still see that, and the additonal air will be mixed before reaching the converter.

    Perhaps you could just put a 4 tube AIR manifold in place of the 1 tube though, as long as the upper hose is the same piece...

    [/ QUOTE ]
    My 88 Shop manual mentions this. They did run all the time for the most part on the Carb equipped. When they went FI it mentions that they only run when warming up. After warm they stop pumping the air in. On y 88 with bad manifold gasket you can hear it change when it quits introducing air.

    That things days are numbered. I don't have to smog it because it's 8600lb GVWR /forums/images/graemlins/woot.gif They may be gone next week. My buddy is lending me a hand changing out the gaskets and drilling out broken manifold bolts. He happens to have a set of factory stainless headers with screwed up Air stuff. We are going to drill then tap them and plug if I can talk him out of them. /forums/images/graemlins/peace.gif Pop my factory Y pip off and make a new one to match the headers.
     

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