So I just finished installing the intake gasket and o-rings on my '79. Fired it up last night. At first I thought I must have done something wrong with the gasket/o-rings 'cause it was smoking like crazy after the engine and exhaust heated up. THen I realized the anti-freeze had run down the side of engine and exhaust when I had taken the manifold off. So it was just the residue.

The car ran rough at low idle (under 1000 RPM) so adjusted the air mixture screw until it smoothed out. It was getting late so I shut off and left it for the night.

I started it this morning and was happy to see no white smoke come out of the exhaust, no smoke from the exhaust manifold. But it was dark in the garage and I noticed a flame coming from the small pipe by the exhaust which I thought was supposed to carry only cooling air. Is this normal or did I mess something up when I changed the mixture?

 

If you had to change your mixture, and it ran fine before, start looking for vacuum leaks. Not sure which pipe you're refering to, but it could be the mixture change and vacuum leak, or perhaps timing if you've adjusted that. Find the vacuum leak 1st, then return the mixture to what it was before. Don't wory about timing until you have solved the other issues.