WE HAD A CUSTOMER COME TO US WITH SOME FUEL DISTRIBUTION PROBLEMS ON THE SV1 CARB. TO ADDRESS THIS WE DEVELOPED AND MADE THESE CUSTOM TAPERED SPACERS. THIS SPACER IS 2 TALL AND WORK. IF YOU HAVE A SV1 CARB YOU NEED ONE OF THESE SPACERS. THEY ARE MADE TO ORDER AND CAN BE MADE WITH PORTS FOR SENSORS OR A LEANOUT FOR ALCOHOL. PLEASE CALL US WITH ANY QUESTIONS. 802-372-8565