Holley stumble trouble
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.
PUZACTLY (as RRR says) is what I think the issue is. Drill put the main air bleed .004-.006 thou and go test.
The issue is IF you go to big, it’s harder to go back. That’s why screw in brass is so bitchin’ (what is that??? a right out of the late 1980’s saying??? yes I’m old) because if you have changeable brass it’s cheap to replace.
If you do go too big, you can buy replacement OE brass bleeds from BLP with the correct hole in them.
You’ve got to get it on the booster quicker, and when you do, you’ll probably find you’ll need T slot restricters, which is an easy modification.
Get it one the booster quicker and see what happens.
BTW, I was talking to FABO member lead69 last night and this very topic came up. We both believe that Holley sends out all these “universal” “performance” carbs so nasty pig rich that you can get away with a late opening power valve, which when you get the power valve opening at the right time, you are now even more pig rich than you were before.
So there was some method to the madness of how these carbs came out of the box. It’s insane, but that’s besides the point.
Once you start correcting the idle, transition and cruise circuits by leaning them out and cleaning them up, you end up with the booster being delayed because it’s no longer fat. You had excess fuel there when the car was pig rich and now you don’t, so it makes it seem like you’re getting on the booster too late, but booster timing was retarded because it could be. Now it can’t. Also you need to remember that the engine mostly runs off the fuel puddle in the bottom of the intake...I hope I’m getting that correct but I’m pretty sure I am.
I hope this makes sense. I know I say it better than I type it, and I don’t say it very well.