tunnel ram tunning help 408sb

hi i have a 408sb with tunnel ram, carburetor I use is 2 x 390 cfm, the engine runs fine on until you press full throttle then it begins to (Counterattack) I can not really describe how it sounds. it feels like it may be gets too little gasoline.
carburettor is restored, and I currently have 54 nozzle in the front of the carbs and 64 nozzel at the back. carburetors are vacuum secundaris,

I'm bad at writing in English / simon from sweden