Edelbrock 1841 Thunder Series AVS Carburetor Calibration Kit Designed to tune cars to match any engine Includes an assortment of metering rods and jets Offers more volume with inlet for total fuel plumbing flexibility Components and quantities are specifically tailored for each carburetor This kit includes an assortment of metering rods and jets, a pair of metering rod retaining springs, and a complete assortment of step-up springs