Can someone describe to me how to check the float level or to see if I've got dirt in my needle and seat on my 70 quadrajet which may be causing a rich mixture? It was recently rebuilt.

To check the float level you're gonna need one of those little L-shaped rulers that come with the Q-jet rebuild kit.The kits also have all the specs for the carb as well.They usually cost about $15.00 from Autozone,Napa,etc. Just give them the number on the carb and they can get you the right kit...As far as dirt in the needle & seat, the only way to tell is to remove the top of the carb,remove the float(it should have the needle hanging off it), and look down into the seat to see if there is any crud in there...But if your gonna do that, might as well get the kit and check everything at once.....my .02$

Q jet floats are prone to sinking. Maybe thats your problem. If your carb was rebuilt and the float wasn't changed, do it now. The floats are cheap. You don't need to buy another kit, just set the new float so it's about 3/16 down from the top edge of the float bowl when it's all the way up.