Horrible MPG/Fuel odor troubleshoot

If it is an AFB knock-off, then it has metering rods. Which are controlled by manifold vacuum acting against calibrated springs. Perhaps the calibration is off, or perhaps the metering rod calibration is off, or perhaps the manifold vacuum is off, or perhaps the timing is insufficiently far enough advanced to bring the vacuum up to what the springs are calibrated for. If the system is borderline out-of-whack, and the vacuum advance is not working, the springs can elevate the rods to where cruise might be rich.
Notice all the perhaps and mights.
Start with; making sure the choke is disengaged, that the engine is getting up to temp (180 to 195), that the valves are properly lashed,getting the timing into it, and ensure that the vacuum advance is working, and ensuring that there are no vacuum leaks, and make sure the Vcan is hooked up to the spark-port.Once you have those bugged out, you can move on,to the carb.'Course by now the plugs are probably done.