Alright first things first i'm 18 and i do not know carbs but this is my first classic car refurb. So my setup is a stock 350 with hedman headers and a 750 edlebrock carb. I know the carb is a little too much but i'm planning on mildly building the motor. The problem i am having is the car will not drive past 10 mph without backfiring like hell. I'm thinking this issue is because my car will not idle without the support of my fast idle screw and in return is it pushing too much fuel out when i get into power. Please let me know your thoughts on what this could be it would be much appreciated.

 

Check the timing and look for vacuum leaks.

 

So i retimed the engine and hooked up a vacuum gauge and it is very wobbly i'm guessing this mean vacuum leak?