Carburetor backfire

[Daba]

I have a 31 three window four-door with a B motor the car runs great up until 45 miles an hour anything over 45 it starts to pop through the carburetor any suggestions would be grateful. Carburetor adjustment? Timing adjustment? fuel mixture adjustment? drive the car off a cliff ?? Lol
Thanks again Daba








31 three window four-door deluxe with B motor
31 slant window four-door deluxe