Began wowrk on the carb heat system. Made a heat selection flap valve from 0.063" aluminum sheet welded to a 1/4" aluminum shaft. Drilled holes in the air box to accept the shaft. Fabricated an actuator arm from 1/4" thich 7075 T6 aluminum. Drilled a 1/4" hole in one end to mount to the shaft and a 3/16" hole in the other end to mount the ball joint connection to the control cable. Split the end of the arm so the arm could be clamped arond the 1/4" shaft. Drilled a transverse hole through the split arm end and tapped for 8-32 screw for providing the clamping force.