Classic/Antique Car Repair: Timing, distributor cap, dick

Question
I recently had my engine rebuilt and the guy that removed dissapeared .So I've had a friend install and he has it running but unlike V-8 engines I thought I could loosen the Original Distributor and advance or decrease it to make it not through so much Black smoke out now replaced Tailpipe system.I've also noted that the little what looks like an adjustable knob just below the Distributor Cap.I've turned this but dosen't change anything.It also hit's Block when trying to turn Clockwise.Please advise if You can  

Answer
Please tell me the make and model of your car, and which engine it has, and whether anything is non-original - I can't guess at those things, and they do affect the answer.

If you are getting black smoke out of the tailpipe, you have a carburetor problem - that black smoke is carbon, and that comes from partially burnt fuel.

Post a follow up question to me with some more information and I can probably help you.

Dick