Backfire issues

[Froggys86]

Have a 81 el camino v6, replaced carburetor, vacuum lines, spark plug and wires, and did timing...it starts right up and drives good just that it backfires, could someone please.let .e know what it could be? Thanks in advance all and any replies is highly appreciated.

 

[airboatgreg]

When does it backfire? Cold, hot, idle, light acceleration, hard acceleration? Is it backfiring through the carb? exhaust?

 

[Froggys86]

When does it backfire? Cold, hot, idle, light acceleration, hard acceleration? Is it backfiring through the carb? exhaust?

Hot with light acceleration and thru carb

 

[Clone TIE Pilot]

Likely its because the fuel mixture is lean, probably a vacuum leak somewhere. Also could be a broken intake valve spring.

 

[airboatgreg]

Hot with light acceleration and thru carb

When it backfires do you feel a skip? Will it back fire consistently or when it feels like it?

 

[83MonteCarloSS]

Have you checked timing? It sounds like your base timing is good but what is the base timing? How much mechanical advance? How much vacuum advance?