Rebuilding Q-jet

[truckin 79]

I have been tearing apart my q-jet because of strong smell of gas when driving. Well when I took top plate of Q-jet off there was a broken pencil tip in the top of the vent tube??????? Some kind of Q-jet tuning I have never heard off LOL. I was also surprised to see threaded bolts(why would they be there, see pic) on either side of carb. Every time I open a q-jet I find interesting things that have been done to them. Anyway I think I inhaled to much carb cleaner fumes since I don't remember what is the base setting for idle mixture screws on a 4 barrel Q-jet. Do most people do 2 1/2 turns or 3 1/2 turns from bottomed out? On my 79 the idle screws were all the way closed down and with that pencil stuck in vent tube I am surprised the truck even ran down the road. My dad said this carb came from Advance auto and so that might explain why it was so beat up.