Tuneup change with barrel valve?

Discussion in 'PSI Superchargers Tech Questions' started by Bjs344, Oct 12, 2023.

  1. Bjs344

    Bjs344 Member

    Joined:
    Sep 10, 2013
    Messages:
    355
    Likes Received:
    24
    Bbc, 14-71, 990 pump. ~32 psi boost. I had a homemade system with a hilborn can below the shutoff acting as the main pill. I capped that and added a k-valve on the hat (like most use). Would you expect much difference in fuel flow if I used the same size main?
     
    #1
    Bjs344, Oct 12, 2023
  2. Bjs344

    Bjs344 Member

    Joined:
    Sep 10, 2013
    Messages:
    355
    Likes Received:
    24
    In case anybody was curious, I Went from a .130 to a .135 to get a similar plug.
     
    #2
    Bjs344, Oct 17, 2023
  3. Mike Canter

    Mike Canter Top Dragster
    Staff Member

    Joined:
    Mar 10, 2004
    Messages:
    4,630
    Likes Received:
    189
    A 5 jet at 130 is such a small percentage of change I really doubt you would notice the difference
     
    #3
    Mike Canter, Nov 1, 2023
  4. kosky racing

    kosky racing Comp Eliminator

    Joined:
    May 11, 2003
    Messages:
    890
    Likes Received:
    48
    Mike that is almost .40 of a gallon-not a small change
     
    #4
    kosky racing, Nov 3, 2023
  5. Mike Canter

    Mike Canter Top Dragster
    Staff Member

    Joined:
    Mar 10, 2004
    Messages:
    4,630
    Likes Received:
    189
    But when you are using a jet that big that is flowing that much the percent of change is very small. If you had a 65 main jet the change of 5 would be big
     
    #5
    Mike Canter, Nov 6, 2023
  6. kosky racing

    kosky racing Comp Eliminator

    Joined:
    May 11, 2003
    Messages:
    890
    Likes Received:
    48
    that is true but it still is almost.4gallons
     
    #6
    kosky racing, Nov 7, 2023
  7. Mike Canter

    Mike Canter Top Dragster
    Staff Member

    Joined:
    Mar 10, 2004
    Messages:
    4,630
    Likes Received:
    189
    Lots of racer (not me or you) only change the main jet by five sizes at a time
     
    #7
    Mike Canter, Nov 8, 2023
  8. kosky racing

    kosky racing Comp Eliminator

    Joined:
    May 11, 2003
    Messages:
    890
    Likes Received:
    48
    I go be the size of the main jet that is in it
     
    #8
    kosky racing, Nov 8, 2023
  9. Bjs344

    Bjs344 Member

    Joined:
    Sep 10, 2013
    Messages:
    355
    Likes Received:
    24
    I change by 5 at 100 or above. 3 or 4 below 100.
    I promise I can see the difference on the plug going from .130 to .135
     
    #9
    Bjs344, Nov 10, 2023
  10. kosky racing

    kosky racing Comp Eliminator

    Joined:
    May 11, 2003
    Messages:
    890
    Likes Received:
    48
    yes you would see a difference but you are going the wrong way when small you make a bigger step when a large number a smaller step
     
    #10
    kosky racing, Nov 10, 2023
  11. rcparker

    rcparker New Member

    Joined:
    Mar 10, 2010
    Messages:
    25
    Likes Received:
    0
    Old-New÷Old×100=%change. Valuable formula for figuring % of area change
     
    #11
    rcparker, Nov 11, 2023

Share This Page





XenPorta 2 PRO © Jason Axelrod from 8WAYRUN.COM