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  1. #1
    garyow73
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    Default Exhaust Manifolds

    I have a 1973 Convertible with factiry air conditioning, 4 speed and L82 engine with smog pump. I have had it since new. It has a 21/2" exhaust system which is in need of replacement. While inspecting the exhaust I noticed that about 3" from the exhaust manifold the 21/2" pipe was downsized to 2" with a very shabby looking welds on both sides. Should the car not have 21/2" outlet exhaust manifolds being the rest of the system is 21/2"? I have not been able to locate any 21/2" manifolds that have smog fitting bungs. Thanks for any information.

  2. #2
    Exhaust Manifolds
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    What you see is normal. 1965 was the last year small-block Corvettes had 2-1/2" exhaust manifold outlets. There's no such thing as 2-1/2" exhaust manifolds with A.I.R. fitting holes - all A.I.R. and non-A.I.R. manifolds from 1966-up were 2".

    After 1965, Corvettes with 2-1/2" exhaust systems had the factory pipes swaged down to 2" just below the joint at the exhaust manifold outlet; most replacements had a weld joint there instead of the swaged diameter reduction.


  3. #3
    Jimmy C
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    Quote Originally Posted by JohnZ View Post
    What you see is normal. 1965 was the last year small-block Corvettes had 2-1/2" exhaust manifold outlets. There's no such thing as 2-1/2" exhaust manifolds with A.I.R. fitting holes - all A.I.R. and non-A.I.R. manifolds from 1966-up were 2".

    After 1965, Corvettes with 2-1/2" exhaust systems had the factory pipes swaged down to 2" just below the joint at the exhaust manifold outlet; most replacements had a weld joint there instead of the swaged diameter reduction.

    JohnZ,
    That is some great info. I just popped this topic up to read it and am impressed w/ the info you posted. Keep up the good work. Thanks.

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