Help.......backfiring

[FiatJack]

I have '79 Spider 2000. Just had the carb rebuilt and intake manifold gasket replaced. Since these repairs, car backfires when I let off to shift. My guy indicates that I need new EGR valve to solve the problem. Also he noted that he blocked off the EGR valve. Any insights on a possible solution would help. Thanks Jack

[majicwrench]

Get a new guy. EGR not causing that. Backfire is from fuel burning in exhaust. If it didn't do it before repairs, and does it now, methinks something is missing/disconnected. Exhaust leaks can contribute, but that would not have changed with repair. Engine has some sort of boost controlled decell device ( to let engine return to idle slowly) that feature has to work correctly. Lots of options. Hows it run?

[FiatJack]

Runs great. Much stronger after rebuild. Was idling up and down a little so I backed off the mixture screw a little and increased idle screw slightly. Runs really good.