Help with my 4150.

[-=Z28=-]

Hi, fairly new here. I received a lot of help in the ignition department regarding my 6530. Now that that's working good I'm back on tuning my carb. Little back info,
Car is a '84 Z28 (2800#)
Tran is a 700R4 built by Ruthless Racing.
Rear is a Ford 8.8" with 3.73 gears.
Engine is a 383", 10.75:1
RPM Air-Gap.
Custom cam by Powell machine
232°/233° .545"/.547" @ .050" 106° ICL, 110° LSA.
All roller.
Engine dynoed 460 HP, 500 TQ
71 & 83 jets.

Car starts and idles great. AFR is 13.6 or so. Issue is when I stomp on it, it falls flat on its face for a second, pops lightly from exhaust, and then takes off.
Thinking I need to check accelerator pumps, although I'm sure they're set right.
Unfortunately, I didnt look at AFR when this happened. Car paint is fresh and I live on gravel road and haven't gotten chance to take it to tar yet. Tabs and insurance come tomorrow. Try a bigger nozzle? Different cam? Floats are good, transfer slots not overly exposed, idle air screws out one turn in all four corners. Running T4 from VP fuels now. Thanks all, Dan

[-=Z28=-]

I tried going from a 28 to 31 in primaries and it made it worse. I'm going to try more initial timing and see it that helps. Currently I have distributor locked at 35°, pulling 22° from 0 to 1000 and all in by 2750 RPM.

[Gaz64]

Hello Dan.
What carb you have here?
What color pump cams?
And your pump cam adjustments are correct? Gary

[-=Z28=-]

750 DP, mech secondary. Looks to be a red cam in #1 position.
Yes sir, any movement of throttle produces fuel to come from the nozzles. I changed initial timing to 18°. It definitely got better. May go to 20° initial after work and see how it does. Thanks.

[Gaz64]

18° sounds like a better timing value for your engine/cam combo.
The red cam is tiny, even smaller than white. Might want to get yourself a pump cam assortment: https://www.holley.com/products/fuel...ts/parts/20-12. Gary