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    Results 1 to 3 of 3
    1. #1
      Join Date
      Mar 2009
      Location
      left coast
      Posts
      145
      Country Flag: United States

      air bleed question

      Super happy with my first time tuning on a 600/VS 4150 last year for autox. Actually got it right, no stumbles, bogs, or problems all year. I guess that's what books and innerweb are for. Trying to do some learning and reading up on perf carb tuning so I can take it up a notch this year. One aspect I can't seem to wrap my head around. When working with idle bleeds and high speed bleeds on the demon, qft, and holley, is it practice to change all four H/S bleeds (primary & secondary) simultaneously, or do you treat the primary H/S bleeds separate from the secondary H/S bleeds when tuning? Nothing I've read identifies this.

    2. #2
      Join Date
      Mar 2009
      Location
      left coast
      Posts
      145
      Country Flag: United States
      My suspicions were correct, found the answer. To better manage the fuel curve, treating the pri and sec HSAB individually is best approach. I also see you need to visit other options before diving into the air bleeds, like small adjustments to the float levels, adj'ing the front IFR richer/leaner then rear IFR, PV and/or PVCR's, etc, etc.

    3. #3
      Sounds like you are on the right "track" - pun intended...

      Since you are autox'ing the car, changing to a 700-750 cfm carb body and adding modular annular boosters is another move forward for throttle response and mid-range improvements over the standard straight leg boosters in the 600 carbs, allowing you an increase in CFM, along with even better drivability and power.

      When we did a lot of custom carb work, most of the extra mid-range power we found was from the annular booster design, using excellent billet metering blocks with adjustable orifices everywhere. We did the fine tuning with the air bleeds for the razors edge tune.....

      Remember that the last place the fuel actually leaves the carb is from the Booster, so you want the best atomization possible for the best power at all parts of the curve.





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