Welcome to Club Hot Rod!  The premier site for everything to do with Hot Rod, Customs, Low Riders, Rat Rods, and more. 

  •  » Members from all over the US and the world!
  •  » Help from all over the world for your questions
  •  » Build logs for you and all members
  •  » Blogs
  •  » Image Gallery
  •  » Many thousands of members and hundreds of thousands of posts! 

YES! I want to register an account for free right now!  p.s.: For registered members this ad will NOT show

 

Thread: Carburetor Size??
          
   
   

Reply To Thread
Page 2 of 2 FirstFirst 1 2
Results 16 to 20 of 20
  1. #16
    1wild&crazyguy is offline CHR Member Visit my Photo Gallery
    Join Date
    Feb 2010
    Location
    vista
    Posts
    18

    quadrajets have theee worst secondary metering system on the planet which consist of a set of what I call 'piss tubes' and what others call spray bars.
    The primarys are so tiny, which house large [compared to the primary venturi size] boosters which together give great low end/milage but offer lil cfm in relation to the secondarys huge flow..which only strengthens the argument for why the heck couldn't they of come up with something better than 'piss tubes' and no boosters..

    If it wasn't for stock class/fast class rules they would have all been recycled by now, and rightfully so.
    A thermoquad is better piece, and I still would not recommend it for what you are doing because it is to a ventilated dinosaur bone.

    nothing meters as well as a square bore.
    Yes you are able to more fine tune the cruise with metering rods.. but in the end you'll short power wise with spread bore.

    How big a carb you can get away with [without sacrificing low end] will directly relate to tune/compression.
    The cam already gives us a power band or rpm, so now it's a usage requirement.

    How much initial timing do you run for right now?

  2. #17
    1wild&crazyguy is offline CHR Member Visit my Photo Gallery
    Join Date
    Feb 2010
    Location
    vista
    Posts
    18

    750-830 annular square bore.

    spread bore carbs have poor wot metering.

    quadrajets have sewer pipes for secondarys, if it weren't for class rules they be recycled.

  3. #18
    sooper's Avatar
    sooper is offline CHR Member Visit my Photo Gallery
    Join Date
    Jul 2010
    Location
    Renfrew
    Posts
    26

    Quote Originally Posted by kens383stroker View Post
    I have a 383 stroker, aluminum heads 64cc, aluminum roller rockers, 557 cam ( not sure of duration) Looking for a good 750 carb for it. Thanks
    Bye bye throttle response

  4. #19
    brattrw is offline CHR Member Visit my Photo Gallery
    Join Date
    Oct 2010
    Location
    Columbia
    Car Year, Make, Model: Looking ...
    Posts
    12

    A good formula is (displacement x rpm)/3,456. This formula assumes 100% volumetric efficiency (VE). A strong street motor will usually be around 85% VE, a race motor may be close to 100%. Take the results from the formula x your approximate VE. For example, if you plan to turn your 383 6,000 r.pm., and it's a street motor, 383 x 6000/3456 = 664.73 x .85 = 556.19 cfm air flow, so a 600 should work well.

    This is what I have used in the past. Is this not a good formula?
    Please check out http://www.s-wracing.com

    To finish first, first you have to finish!

  5. #20
    tango's Avatar
    tango is offline CHR Member Visit my Photo Gallery
    Join Date
    Nov 2007
    Location
    Chicago
    Posts
    1,354

    Quote Originally Posted by 1wild&crazyguy View Post
    750-830 annular square bore.

    spread bore carbs have poor wot metering.

    quadrajets have sewer pipes for secondarys, if it weren't for class rules they be recycled.
    I agree with Wild . Q-Jet's work ok on Stock to Mild Street Engines . And they have a Nice Rolling Punch to them . But they are Problematic in many ways and way over Price-ed . You never hear the true negative Side to them small front to Large rear barrels . I have worked on the Very First Q-Jet Models and the Computer one's and Know how to Mod them if I have to use one . I have one on My SB Chevy Pick up . It work's ok it has some of the normal Q-Jet Problems . I am saving for a Edelbrock Performer carb to replace it And them what you call sewer pipes a Lot of the Time fall out into the secondary fuel well . I have had some fun with Q-Jets but they ain't what Folks try and make them up to be .
    Wisdom is acquired by experience, not just by age

Reply To Thread
Page 2 of 2 FirstFirst 1 2

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
Links monetized by VigLink