I've seen several posts on issues with Q-jet tuning lately, and it jogged my memory about something I did which may be helpful for others. One of the big problems with tuning a carb is knowing if you are rich or lean and when. I used an air/fuel ratio gage (w/LED's ) and an O2 sensor from Summit to tune my Q-Jet after I built my 383. I had a muffler shop weld a bung in the pass. side header collector (it's only 1/2 the engine, but it worked -just treat the other half the same), then wired it up. Total cost approx. $70. It was very simple to see the results of idle mixture changes, rod and jet changes, air filter/housing changes, etc. It's very helpful especially if you need to pass emmissions. I dialed mine in and it passed easily. The real plus is that it runs great. Anyway, hope this helps someone out.