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  1. #1
    Join Date
    Jul 2002
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    Mesquite, TX
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    How much dimple is too much?

    1 5/8" primary headers on an LS1.

    It looks like if I dimple both front pipes for frame clearance about 1/4" it'll cure all my (header routing) woes and I won't have to make nearly as many other changes to the headers.

    Will this completely ruin performance? It looks like cutting and rewelding the flanges will just create other issues - I'm awful close to the starter as it sits, and I'd end up closer, etc.

  2. #2
    Join Date
    Aug 2008
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    jacksonville,fl
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    I always here the term dent or dimple header for clearance which would mean concaving the pipe in , which would create some restriction. However if you more skillfully oval or d-shape the pipe, then you retain the same exact internal volume. Make sense? If you hold a block of wood, flat metal plate, etc over pipe & hammer it, you can more oval the pipe rather than dent it. Grab a cheap 1 5/8"pipe extension from auto store to practice on if needed.
    In general, dents don't always really lower performance, mostly because many engine have larger than really needed headers. In your case, yours are not bigger than needed,so should be more carefully handled.

  3. #3
    Join Date
    Jul 2002
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    That makes sense, thank you. The practice piece is a great idea.

  4. #4
    Join Date
    Nov 2006
    Location
    Mountain Springs, Texas
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    1969 Camaro - LSA 6L90E AME sub/IRS
    1957 Buick Caballero - huge project
    1959 El Camino - Ironworks frame
    1969 Mustang Sportsroof
    1956 Cameo - full C5 suspension/drivetrain

  5. #5
    Join Date
    Jul 2002
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    Mesquite, TX
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    Thank you very much, Don, I feel a LOT better now.

    Hell, I'm only dimpling two tubes, I may gain horsepower!

  6. #6
    Join Date
    Nov 2009
    Location
    Peoria, Az
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  7. #7
    Join Date
    Jul 2002
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    I think that's the same video Don posted (just on a different site). I don't have a subscription so I can't watch to verify.


  8. #8
    Join Date
    Nov 2009
    Location
    Peoria, Az
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    I think you're right. Sign up for the 14 day trial. There are a ton of good shows on there.