I have had a Holley 750 vacuum secondary, a Holley 750,850, and 950 HP on my car over the years, none ran as quick or nearly as well as the Q-Jet. I’m convinced the bad reputation Q-Jets get is from poor rebuilding practices. Let’s face it, the newest Q-Jet is 30 plus years old. Your not going to fix decades of wear with a 30 dollar rebuild kit and a can of carb cleaner from Autozone.