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.

[oldpurple]

The one on the outside is for idle speed. It's really just an adjustable stopper for the throttle body

[truckin 79]

Yeah not the idle speed adjuster just below it you can see a darker round circle inside the carb body. That is the screw that was placed in the bowl right there, you can actually see some threads poking out of the hole.

[oldpurple]

Oh I see it now. That's weird. Maybe someones attempt to straighten out some warpage?

[ron350]

That hole that the screw is stuck in is part of the idle air bypass system used on some Q-jets.

Make sure you put that secondary vent tube back in the hole it fell out of.