Terry is the chief car tester for Emery Motors and Frank is an Engineer. Jane has just been hired to work in publicity. Frank and Terry both want Jane to be their girl. Terry has designed a new carburetor that should bring him fame and money, but he cannot get it to work correctly. Terry and Gadget have tested it for over a year, but it still is not perfected. Emery Motors assigns Frank to help Terry with the carburetor, but Terry is not happy because Frank is an Engineer and is also vying for Jane. They finish the carburetor, and to test it, they enter a car in the Indianapolis 500 race. Terry is not yet satisfied with the carburetor before the big race even though it has passed all the tests.