Holley stumble trouble

SSG_Karg said

30cc pumps front/rear. 28 squirter front 31 rear.
I don’t think it has anything to do with the acc pump. If I mat the throttle it takes off, no hesitation or stumble at all. Only hiccup is during very light throttle cruise when starting to give it a hair more throttle. Just a half second hiccup then smoothes back out. If I get into the throttle quickly it doesn’t stumble. Seems like the transition is not lasting long enough until the mains can take over.

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You need to buy a 61-80 drill bit set and find out what the IFR, IAB, and MAB sizes are. Without knowing you are just guessing. Someone may have previously gotten that carb out of whack. In the 2-3k rpm range the carb is going back and forth between the idle/transition circuit and primary depending on gear and load. To extend and richen the transition circuit a larger IFR and smaller IAB is needed. As an example if you currently have .031 IFR/.070 IAB you would fatten the circuit to .033 IFR/ .067 IAB. You only have to do this on the primary block.