'70 LT-1 EXHAUST MANIFOLDS

Discussion in 'Engine Topic' started by ThomasD., Nov 21, 2017.

  1. ThomasD.

    ThomasD. Veteran Member Lifetime Gold Member

    217
    3
    Feb 23, 2010
    Fairbanks, Alaska
     
  2. ThomasD.

    ThomasD. Veteran Member Lifetime Gold Member

    217
    3
    Feb 23, 2010
    Fairbanks, Alaska
    Sorry, messed up that last post.
    So, the tubes aren't attached to the plugs? I'll need to really soak them then, cause the plugs aren't budging.
     
  3. COPO

    COPO Veteran Member Lifetime Gold Member

    15,928
    180
    Sep 15, 1999
    Ontario, Canada
    No the tubes come out. I removed all of mine and cleaned them up on a drill press and sand paper.
    The AIR pump shoots air into the exhaust valves for pollution control. I had mine off from 1985 to about
    2003. I never thought I'd ever install them back on. Luckily I stored all my Smog in a Box.
    [​IMG]

    [​IMG]
     
    Last edited: Nov 21, 2017
  4. 70lt1z28

    70lt1z28 Veteran Member Gold Member

    1,275
    138
    Oct 3, 1999
    Beavercreek, Ohio, USA
    To help get the plugs out, heat the area with a propane torch and the shoot with PB Blaster. May have to do this a couple times. Then try breaking them loose.
     
  5. flowjoe

    flowjoe Moderator Staff Member Lifetime Gold Member

    7,941
    21
    Feb 7, 2006
    SoCal
    I don’t think it’s the Holley’s fault Gary. The engines that came Holley equipped from GM were also very high compression compared to other production engines and had high lift cam shafts...none of which is conducive to hitting smog numbers.
     
  6. flowjoe

    flowjoe Moderator Staff Member Lifetime Gold Member

    7,941
    21
    Feb 7, 2006
    SoCal
    As mentioned above, probably a service replacement. I’d hang on to them given your car’s unique history in your family. Close enough to original and part of your car’s story.

    My 69 Z had plugs installed when I bought it in ‘84. Eventually I sourced the whole AIR system and went about setting it up. The plugs were in there good but finally gave up the fight and let me remove them. The problem was that some of the threads in the manifold had eroded and would not seat the AIR the fittings. Hopefully yours will be more cooperative.
     
  7. Ricks72Z28

    Ricks72Z28 Veteran Member Lifetime Gold Member

    800
    5
    Jan 1, 2005
    Schererville,In.46375
    When and if you remove the smog tubes and plan to replace them...make sure you keep the originals for measuring the length.The NOS ones are too long and will need to be cut down.
     
  8. ThomasD.

    ThomasD. Veteran Member Lifetime Gold Member

    217
    3
    Feb 23, 2010
    Fairbanks, Alaska
    So The tubes are protruding through the manifold into the port and plugs are installed on this factory LT-1 manifold. Was this the way they came from the factory? Were these the same manifolds used for the base 350 that had the AIR system installed? Just seems odd to
    Have that obstruction in the port of a ‘performance’ engine.
     
  9. Ricks72Z28

    Ricks72Z28 Veteran Member Lifetime Gold Member

    800
    5
    Jan 1, 2005
    Schererville,In.46375
  10. COPO

    COPO Veteran Member Lifetime Gold Member

    15,928
    180
    Sep 15, 1999
    Ontario, Canada
    Any car that came with A.I.R. got them. Why is this hard to believe? 68-69 Z/28's had them too. Same with Chevelles.

    69 Z/28
    [​IMG]

    68 Z/28
    [​IMG]

    70 LS6 Chevelle
    [​IMG]
     

Share This Page