I had the carb rebuilt. They told me that they tuned it and it should be plug and play.
Once i got the engine warmed up and tried to take around the block. It idled well, but once I put it in gear it sputtered. I couldn't get it to run much unless I closed the choke half way.
I got it back and adjusted the idle to 600, down from 1000 with the choke open. Drove it again, same problem.
I screwed in the fuel mix screw all the way, backed it out 1.5 turns. From there if I back it out any further the RPMs drop. If I turn it in, the RPMs drop. As I understand that is the ideal spot.
I tried driving it again, it did a little better, but as I got a little more speed on it and shifted into second it back fired twice, blowing the air cleaner into the street. I ran it over

Now what? I don't seem to have a mark on the flywheel to adjust the timing, but before I had the carb rebuilt it, timing wasn't an issue.
Any other ideas?