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Trying to lean out cruise while keeping full throttle and transition the same

Discussion in 'Carburetor + Boost Tech Questions' started by racin69z, Oct 8, 2022.

  1. racin69z

    Joined:
    Nov 13, 2008
    I have a 408 LS in a 5300# lifted redneck truck. I did a home built 830 annular with the hangar 18 mods vent tube extensions and the Brent Davis crutch using turbine pressure to open the PV back in 2012. It gets the job done, low 11s under boost (only 8# right now). I only drive it around 500 miles a year but the the part throttle driveability isn't great. To maintain 55 mph on flat ground it takes around 1/8 throttle. AFR at that point is 12.5-12.9. Get on it a bit more 1/4 throttle to accelerate and it will get up to around 13.8-14.1ish.

    I was gonna pull jet and increase PVCR but that will make the 1/4 throttle pretty lean. I was considering increasing idle air bleed a little, but im not sure that will do it. Is the idle air bleed in play at 1/8 throttle? I know the transition slot is uncovered, but im not sure if any fuel is coming out of the idle circuit at that point.
    Any thoughts or other ideas?

    Thanks for any ideas
     
    racin69z, Oct 8, 2022
    #1

  2. tbird

    Joined:
    Sep 1, 2004
    what rpm at 55mph?

    Idle air bleed has effect on the idle and transition circuit.
     
    tbird, Oct 12, 2022
    #2

  3. racin69z

    Joined:
    Nov 13, 2008
    It turns around 2500 rpm at 55mph.
     
    racin69z, Oct 12, 2022
    #3

  4. tbird

    Joined:
    Sep 1, 2004
    what is your ifr and iab currently?
    Gasoline?
     
    tbird, Oct 13, 2022
    #4

  5. Mnlx

    Joined:
    Sep 20, 2009
    What's your idle afr? Have you tried leaning the idle?
     
    Mnlx, Oct 15, 2022
    #5

  6. racin69z

    Joined:
    Nov 13, 2008
    It is a gasoline application. I have not messed with the ifr, but i can't remember if i messed with air bleeds or not.
     
    racin69z, Oct 16, 2022
    #6
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