[Excaliber]

Of course a carb could cause the same symptoms, as well as EFI, if either one is running well on the rich side for whatever reason. Slightly ruptured or leaking power valve in a carb comes to mind. Or simply jetting that is way to rich. Certainly a stuck injector in the case of EFI. But running rich is only one possible cause of a backfire, there are others.

In the case of the old "air injecting" via a "smog pump" it was more common to have a backfire condition. The smog pump, pumps, fresh air into the exhaust system on purpose!