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Thread: Upgrading Carb & Carb Size

  1. #1
    Join Date
    Jun 2010
    Jamestown, NY

    Default Upgrading Carb & Carb Size

    Hello all. I'm just getting curious about maybe upgrading my current 650 Street HP Double pumper.
    My setup is in a '91 S10.
    350 .060" over.
    Brodix IK180 Heads.
    Mid length ceramic headers going into an X pipe, through two Super 40 Flowmasters.
    RPM Air-Gap intake.
    Hyper, flat top pistons.
    Comp Cams XE274 cam.
    Steel crank.
    3000 stall converter hooked up to a TH350, with a Ford 9 inch out back, with 3.90s for gears limited slip.
    MSD ignition.

    I have a wideband O2 gauge to help tune, and the 650 I had to lean down quite a bit to get a good A/F ratio.
    I don't believe it's too big of a carb, but was wondering if it may be too small?
    Would a 750 wake this thing up anymore, or would it be a waste of time and tuning effort.
    I just don't want to leave any power on the table if it can be had. Thanks for any replies.

  2. #2


    Personally, I think the gains would be very marginal. That XE274 cam isn't that big at all to justify the 750 double pumper. If you had to lean the 650, I would expect that & some to get the 750 right. All for maybe 10-15 HP. I ran a 750 double pumper on a 383 with Air-Gap, but a XE294HR, and I think it was a tad on the big side for running around the street. WOT and it was great, but on the street how often are you WOT. Part of running the street, "WHAT ARE YOU WILLING TO PUT UP WITH DOWN LOW TO HAVE MORE ON THE BIG END."

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