Edelbrock Carb

I have a 77 silverado with a 350 sb. I installed an edelbrock 600 cfm manual choke carb with an edelbrock performer intake and a new accel distributer. Everything works good except...
At high rev (like passing someone), the motor will "pop", or backfire once it reaches about 3600 - 4000 rpm and continue to do so until you let off the gas. Any suggestions?

sounds like a timing issue to me

basically i agree with both. Make sure timing is correct and check your plugs and wires. i hade a problem similar before and it wasn't the timing or plugs but one of the wire connectors had broken off so it wasn't getting a spark to the plug.