You mount the firewall end, and bracket at base of carb. Pull the "end" off of the carb end of the cable and pull the center 'wire' completely out. Mount the "end" onto the bracket at the carb base and wrap masking tape around the housing then lay the housing beside the bracket/end and allow an extra inch or so for movement. With the housing pressed fully into the mount at the firewall, mark the housing (on the tape) for length at the carb bracket end. Remove housing from the car and put snuggly in a vise. Cut the housing with a fine tooth hacksaw or cutoff wheel. Assemble the housing onto the car. DO NOT CUT INNER CABLE AT THIS TIME!!!! Insert the inner cable (attach to the pedal assembly) and feed through the clamp at throttle linkage of carb. Pull the inner cable out snug with the pedal at the proper height inside. Tighten the screw on the clamp at carb. Test for no bind and full open throttle. If all is good you can then cut the inner cable with SHARP sidecutters, leaving at least an inch or two for adjustments in the future.