Quadrajet is a General Motors carburetor that was used as original equipment on all their V8's, a few inline sixes, and a few V6 engines from the late 1960's to the mid 1980's when they went to computer controlled carbs. Nobody that I'm aware of makes an aftermarket QJ- - - -they're just too expensive to manufacture for anyone to make a profitable clone. Holley tried, with a carb called the "spread-bore" but that didn't last long, IIRC.
Try to find a QJ calibrated for any 5-liter (300-something cubic inch) GM engine, Cnevy, Olds, Cadillac, etc. It will give you good gas mileage with the small bore primary barrels, and the air valve controlled secondary barrels will flow all the air the engine will ever need to run as fast as you dare to hold the throttle wide open. It will outperform anything the hotrodders can bolt on, at a fraction of the cost.
If you believe in the saying "There's no substitute for cubic dollars" go for some of the fancy stuff and spend a lot of unnecessary money.
Jerry
