Holley's ultra carbs come with a notched float instaled in the rear and extensions in the box.The power valve feeds to the main well are lowered to help keep them in the fuel.So just maybe even the big names can learn from us racers.For drag use remove the rear power valve,install the extensions and go up 6 to 8 jet sizes.The aluminum ultra is one of the best race carbs you will find and very adjustable.Bill.