Hand-assembled in the USA, Street Series carburetors from Proform are constructed from 100 percent lightweight aluminum, including interchangeable idle air bleeds, for easy, non-permanent calibration changes. Yes, fine-tuning is done by simply changing air bleeds, so you can leave your drills in your toolbox. Developed for today's high performance engines, these carburetors feature metering blocks with street performance calibration and lightweight, die-cast aluminum bowls with fuel level windows for quick visual reference. Changeable idle feed restrictions expand the idle adjustment capabilities, and 4-corner idle on mechanical secondary models lets you fine-tune the idle for more aggressive cam profiles. Also available with a vacuum secondary, Proform Street Series aluminum carburetors offer easy high performance at a price that you can afford.