A running engine sucks in air thru the carb, so if you smell gas in the engine bay when engine is running then you have a leak in the fuel line or exterior of carb.
Before adjusting the carb you need to set base spark timing.
With engine off turn the two air/fuel screws in until they stop, DO NOT tighten, just until they stop, then turn each one back out 1 full turn then 1/2 a full turn, so 1.5 turns out.
Remove vacuum hose from distributor, plug the hose so no vacuum leaks
Make sure all vacuum ports on intake and carb are used or plugged up.
Loosen distributor so it can be turned but is not too loose
Hook up timing light and start engine
idle needs to be below 1,000 so distributor's mechanical advance isn't being used.
If Choke is on, idle may be higher.
So adjust idle screw if needed to lower idle under 1,000rpm
Set base spark timing at 8 deg. Before TDC
Turn off engine, remove timing light, tighten distributor
Plug distributor vacuum hose back in
Start engine and warm it up
Warm idle should be 650 with manual trans, 750-800 for automatic trans
Hook up vacuum gauge to intake manifold, or lower plate on carb
NOTE: any vacuum port ABOVE the lower plate(throttle plate) on a carb is a PORTED vacuum, not a "regular vacuum", and can't be used for adjusting mixture screws.
Vacuum at idle should be 16+
Adjust mixture screws equally to increase vacuum
You may have to turn idle down or up during this process, to keep it steady
When you have highest vacuum reading you can get you are done.