Coming out of the marine industry, I have a lot of experience with the Q Jet. The vast majority of Inboard/ Outboard and straight Inboard engines built by Mercruiser, Volvo Penta, PleasureCraft, and OMC, to name a few, came off the assembly line with them. They were used on everything from 4.3's to 454's.

The Q Jet is one of the most misunderstood carbs out there, and are actually very good in design and performance. The concept is that you have these two very small primarys that you run on for economy, but when you need more speed you kick in the huge secondaries. I've had a lot of boats with them, and have always marked my throttle with a line at the point where the secondaries were just starting to open. If I kept my throttle below that line the fuel economy was fantastic (I had a 27 foot cruiser that only drank 6 gph) but if you went beyond that mark it started to drink fuel like there was no tomorrow.

Lots of big GM cars came stock with them too, like 472/500 Caddies, 455 Olds, and similar Pontiacs. The racing crowd has never done much with them, why, I am not sure. But lots of street engines have had them on over the years.

Don