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Square bore or Spread bore???

Discussion in 'The Garage' started by bigcat44, May 3, 2005.

  1. bigcat44

    bigcat44 Registered Member

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    I am in the process of installing a Holley 670 Pro Jection TBI on my 89 TBI. I need the adaptor plate to mount the Holley to my Edelbrock Performer manifold but which one do I need?
    this one:
    http://www.holley.com/HiOctn/ProdLine/Products/FMS/FMSFIA/17-41.html

    or this one:
    http://www.holley.com/HiOctn/ProdLine/Products/FMS/FMSFIA/17-45.html

    the 17-45 looks like the stock gasket as far as the 3 holes for the mounting studs but what is the difference? Any help would be greatly appreciated I really want to install this TBI. Thanks in advance
     
  2. Thunder

    Thunder 3/4 ton status

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    End your confusion.This one fits both http://www.cfm-tech.com/catalog/tbi_to_4bbl_intake_adapter_plate_549472.htm
    That is the easist route
    But
    If you want the holley adapter you need to figgure out what kind of a manifold you have
    Edelbrock makes performer manifolds in both square bore and spread bore.

    If you have a manifold that fits a Qudrajet carb or edelbrock 1900 sreies carbs it is a spread bore.

    If your manifold fits a holley or edelbrock 1400 series carb its a square bore.

    And i think some of them fit both kinds. The ones that fit square bore and spread bore have 2 holes in each corner of the carb base.
     
  3. bigcat44

    bigcat44 Registered Member

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    Location:
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    According to my intake manifold Edelbrock Performer #EDL3704
    " Bolt on replacement for stock TBImanifold. Accepts small bore (1 11/16) throttle body injectors. It does not say whether it is square or spread?

    The holley doesn't say anything except it is a stock TBI replacement? Which one should I get??? :confused:
     

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