Fuel system issues, old mechanical type and Qjet

Never officially fixed my issue. I tried a higher volume Carter pump from Summit or Jegs. It has still done it a time or two. I still believe it is a volume and launch issue. Qjets have a wall and restriction back around the secondary needles that I am looking at modifying to get more fuel back there… I thnk under hard acceleration, the car sits back forcing the float upward from fuel slosh. It takes a couple seconds for the float to fall back low enough to allow more fuel in. I think this could be part of the issue. But I really think it is fuel starvation for some reason.

My pump has 3 lines. Threaded line to the carb. One to charcoal canister and one return to tank if I remember correctly. I also run an inline filter between the carb and pump that is the diverter valve style. I capped off the diverter valve and it did not make a difference.

Testing WOT from a roll, no issues as low as 10MPH except tire slip :). WOT from a stop still occasionally sees the issue. It is frustrating when it happens. I also think I noticed it happens uphill worse than down but that may have been coincidence. I just don’t drive it that hard to remember when it happens now.

In my experience float issues show up more than couple of seconds after launching. Usually the bowl(s) can support full demand for longer than that if carb is matched to engine.

What happens if you keep it floored? Does it repeat the stumble or just slowly recover?

@TwinTurbo
I haven’t stayed in it to see. Like I mentioned, I’m not driving it as hard these days and when I do, it is usually from a roll

Pressure regulation, I’d guess. Drop the pressure to 2-3 psi for small throttle opening and allow 6-8 PSI for WOT. I’ve never seen one either.