Missing power 440?

Yesterday I was working with the car. I managed to adjust the lifter preload around 1mm but it didn´t have any change in engine´s performance or ticking noise. I also installed new msd spark plug wires, because old procomp wires were quite bad. This didn´t have any change either. I also ordered roller rocker arms for the engine, that I can easily adjust the lifter preload more accurate per valve in the future.

But then the shocking news!!!
I have old 750cfm edelbrock carb that I installed in its place.
After start up I immediately recognized that engine was running much better and idle was smoother. Then it was time for the test drive. I felt that it is running lean and I changed bigger jets and needles. I went for proper test drive and WOW!! car is fast!!! It easily spins tires with second gear, no more flatspot around 3000-4000rpm :)!!.

So mainly the problem has been this new Quickfuel 850cfm double pumper with annular boosters. I have been changing primary and secondary jets back and forth, accelerator pump nozzles and power valves,cleaning and inspecting but no change. Still the flatspot at 3000-4000rpm and rough idle/shaking. So now after I found the problem, local quickfuel salespoint wants to get the carb back and trying to find reason for this. They told me, that this is second time when they hear this same problem... Interesting to see if they will find the problem. I will update when I´ll know more, but now I will do some burnouts!

Thank you everyone for helping me!:icon_fU: