Getting a backfire

Hey, started the Dart the other day from not having started it in a few months or so. Had a pretty good backfire happening, never had this happen before. Drove it down the driveway, backfire all the way, then parked it again. Would this be a timing issue? Or because I don't have exhaust on it yet? It's running open headers right now because I ran out of $$$. If its timing, do I need to go back to the first step and re set my initial timing? Or is it something I could fix by adjusting my distributor?

Oh, its a stock 318 with an Edelbrock Performer 4bbl intake, a 4bbl carb (not sure the CFM), Hooker headers, Mopar electronic ignition.
Author: admin