I think I might have an engine problem... :(

An 800 double pumper does sound good in theory but if you are just cruising around you may be too rich.If you smell gas at idle you are wasting gas in a street car.Try to find a friend with a smaller carb to test with and get it to temp before checking for issues.As stated that's condensation mixed with soot from too much fuel over time coming out of the exhaust.