Found prob w Holley jet extensions.

I had a frustrating day and night with fuel system setting float on Holley 870. I changed jets on secondary side and then changed needle/seat assy on both sides because seemed to be extra rich. So set float on sec by sight, and when assembled to adjust needle by sight hole couldn't get it to shut off fuel. Luckily I had threaded a tube to catch gas into a can. I had fuel bowl off and on a dozen times trying different needle/seats, float settings, diff floats, etc. It got late and I was frustrated cause I lost a day at drags so I quit. Next day out, I took every thing apart and measured, made sure float was pushing needle. Finally dawned on me that the new jets were different than ones that came out. Dyno tuner guy put jet extensions on to make easier to remove jets from rear secondary side. He had ground a taper on jet (I thought for fuel flow). When I measured it, the new jet without grinding would trap the float in the down position. To fix it so I don't need to grind tapers on every jet, I shortened the extension by .080". Worked fine after that. Somebodies short cut that didn't get communicated cost me a day of fun at drags.