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  1. #1
    Moderator The Bandit's Avatar
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    Drill and Tap question

    Hey guys,
    I just ordered a 1/4 inch NPT tap so I can thread my I/C blockoff for the boost guage. My question is, what size drill bit should I use to make the initial hole? These thread sizes confuse my feeble little mind as 1/4 npt, is 1/2 inch if measured from one side to the other. Thanks in advance


  2. #2
    R-Doo's Avatar
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    Most taps say right on the shank what size bit to use.
    It should be a 7/16 drill.
    Last edited by R-Doo; 11-17-2006 at 11:46 AM. Reason: size matters

  3. #3
    Moderator The Bandit's Avatar
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    Thanks man

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