Holley 2280 throttle bushings

Keep in mind that drill bits do not make round holes, and can often drill holes larger than the size of the drill bit. A better choice is to drill the hole for the bushings undersize by about .010"-.015" and then use a reamer that is about .0015"-.002" smaller than the od of the bushing so it will have an interference fit so it will have a tight seal inside the carb base and not come out under operation.