I suppose it is possible for a carburetor malady to cause a backfire through the carburetor (I don't see how); and I have been working on carburetors since 1959 and have yet to see this.

Think how an engine works.

For a backfire through the carburetor to occur, a cylinder must fire while an intake valve is open, creating a path for the explosion to travel through the intake back to the carburetor.

This condition may be caused by:

(A) an intake valve which is sticking partially open or damaged
(B) an intake valve opening at the wrong time
(C) a cylinder firing at the wrong time

Not saying that the carburetor does not need rebuilding; just that other issues are causing the backfire and should be addressed first.

Jon.

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
If you truly believe "one size fits all," try walking a mile in your spouse's shoes!
The Carburetor Shop