'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
    These came off my wife's LT-1, not going to reuse them long term right now. Just wondering if it would damage their value if I removed the 'port tubes' ( for lack of a proper term ) and plugged the threaded holes for temporary engine break in use since no coated headers are warranted for break in use. Just trying to use what I've already got for the engine start up without buying some other cheap headers. What were these ports used for anyway? Is there any value to these original manifolds?
    Thanks for any input

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  2. Gary S

    Gary S Administrator Lifetime Gold Member

    20,681
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    Apr 14, 1999
    Bismarck, North Dakota
    The ports were for the smog pump to attach to. The Holley carbs were difficult to get to meet emissions so smog pumps were called for. Most engines that year with Quadrajet carbs didn't have the smog pump or the ports on the manifolds.
     
  3. ronzz572

    ronzz572 Veteran Member Lifetime Gold Member

    1,755
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    Feb 8, 2007
    imperial pa
    The manifolds are very desirable to someone who needs them. I can't read the numbers and dates on them. I would be interested in them. If they are correct and for sale? Removing the smog tubes shouldn't hurt them just use a correct threaded plug in the holes. Please email me some better pictures to rgliebertjr@yahoo.com
     
  4. ThomasD.

    ThomasD. Veteran Member Lifetime Gold Member

    217
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    Feb 23, 2010
    Fairbanks, Alaska
    This '70 Lt-1 came with the Holley 4555 I believe, original owner changed the DP 780 to a 750 but these manifolds are the original with the car.
     
  5. ronzz572

    ronzz572 Veteran Member Lifetime Gold Member

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    Feb 8, 2007
    imperial pa
    The manifold ending in 527 is probably original. The 330 is for a 73 more than likely. And also a hard to find manifold for 73 z28 owners.
     
  6. ThomasD.

    ThomasD. Veteran Member Lifetime Gold Member

    217
    3
    Feb 23, 2010
    Fairbanks, Alaska
    Seriously, '73 ?? My wife's father took them off in the late '70's and put on headers. He bought the car from the original owner who had done absolutely nothing to the car except replacing the original AM radio with a Sears & Roebuck 8 track. The manifolds sat on his shelf until he sent them up to us a few years ago. How would I verify that these aren't original?
     
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  7. ThomasD.

    ThomasD. Veteran Member Lifetime Gold Member

    217
    3
    Feb 23, 2010
    Fairbanks, Alaska
    Let me clarify. My wife's father changed out the 4555, not the original owner and apparently tossed it after it sat in his garage for 15 years.
     
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  8. ronzz572

    ronzz572 Veteran Member Lifetime Gold Member

    1,755
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    Feb 8, 2007
    imperial pa
    http://www.nastyz28.com/camaro/z28lt1.html this section covers basic 70 z28 lt1 engine parts. Possibly the 330 manifold was installed to replace a broken or cracked original. When a car is nearly 50 years old. A lot of things are possible. The 330 manifold started production in 1971. The date code on the manifold will give a clue what year it was changed.
     
  9. ThomasD.

    ThomasD. Veteran Member Lifetime Gold Member

    217
    3
    Feb 23, 2010
    Fairbanks, Alaska
    You are correct. The RH is a ‘71-‘72 casting #. So much for being # correct. Thanks for the clarification.
     
  10. COPO

    COPO Veteran Member Lifetime Gold Member

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    Sep 15, 1999
    Ontario, Canada
    Tap the tubes out after a soak in penetrating fluid.
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