Holley Carb help

Sounds like you blew the power valve,but i thought all Holleys came with power valve protectors now?anyway check to see if you blew it,change if you did check/replace base gasket,deffinately check timing and adjustments to carb,use a vacuum gauge when making adjustments...Holley 600's are a pretty basic carb design should'd be hard to figure out.....oh and a heads-up depending on how back it back-fired you might have blown the mufflers too...