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Spread or Square bore?

Discussion in 'The Garage' started by aknight_sa, Nov 11, 2006.

  1. aknight_sa

    aknight_sa 1/2 ton status

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    Hi all,

    i am in the process of planning my project truck... and i just wanted to know what is the difference between square bore and Spread bore carbs?

    thanks
     
  2. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Square bore carbs have all 4 butterflies the same size and spread bore has 2 small primary's and 2 large secondaries.
     
  3. aknight_sa

    aknight_sa 1/2 ton status

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    so what would be better for a truck which is used for a street/Sand application ...
     
  4. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Either carb will do just fine. Most all chevy's come factory with a spread bore quadrajet, most square bore carbs are found on hot rods and race cars but people still use them on trucks as well.
     
  5. aknight_sa

    aknight_sa 1/2 ton status

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    i have been planning on getting the following intake and carb.. will they do well for such an application (both are square bore) do you have a better suggetion or will this be geat?

    Holley Truck Avenger Carb. Part# HLY-0-90670
    Edelbrock Performer intake manifold, Part # EDL-2161


     
  6. pvfjr

    pvfjr 1/2 ton status

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    That'll work good. A lot of people will advise against the Holley Truck Avenger, a lot of people have trouble tuning them. I have one, and think it's a great offroading carb. If you get one though, just make sure before you install it that it's a 90670-2. If it's a -1, or doesn't have a dash #, then you can trade it in to holley for the newer version. There were some bugs that they had to work out of it after it was originally released. Of course, if you're buying it new, it shouldn't be an issue.
     
  7. aknight_sa

    aknight_sa 1/2 ton status

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    thanks for the note....i am buying them new from Summit racing... is there a better place to buy such stuff from???

    also, what other parts would you suggest for a bb 454 engine that might be a better buy than the above?
     
  8. pvfjr

    pvfjr 1/2 ton status

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    You're putting this on a 454? Hmm, the 670 may not do it for you then. I'm running the 670 on my 350. You might have to look into the 770. And yeah, there might be a cheaper place to buy your stuff than summit, but a "better" place to buy stuff would be hard to find. Summit rules, I'd go with them.
     

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