I have a Q-Jet on my `77 350 and it needs some work. Before I give up and buy a rebuilt one, I was hoping to try to tune it properly. Unfortunately, nobody knows how. I've taken to a couple of local shops, and posted on some Chevy forums, and nobody knows how to tune it. They all say they are tricky to tune and a great off-road carb when tuned. I tried doing it the way I've done Holleys years ago: Turn in a mixture screw all the way, then back it out until the idle smooths out, then another 1/4 turn. Repeat for the other screw. Didn't help much for mine .