B&M 20234 Adjustable Vacuum Modulator;

B&M accessories help you complete your project with parts designed and selected by the experts at B&M. This vacuum modulator comes pre-adjusted for 'normal' shift points, but it is fully adjustable, allowing you to customize the shift points (within a range of 2-4 mph). This unit is designed for use with select applications, including GM TH400 and TH350 transmissions. Please note: If you have a big camshaft and your engine does not make adequate vacuum, you will not be able to make the stock or B&M modulator work properly, usually resulting in late, hard shifts.