PLEASE NOTE!
We recommend when installing this kickdown rod that the  correct retaining clips be used on the carburetor and the transmission to retain the kickdown rod. These are provided with the purchase of every kickdown rod we sell. After installation of the rod, check for smooth movement without any binding throughout the full throttle range BEFORE STARTING UP THE ENGINE AND/OR DRIVING the car. Some minor adjusting may be necessary to obtain smooth, unbinding movement. The manufacturer is not responsible for damages resulting from improper installation, use in applications other than that specified or any other conditions beyond his control. NEVER CONNECT THE KICKDOWN ROD DIRECTLY TO THE THROTTLE LEVER ON THE CARBURETOR!  THE PROPER CONNECTION ADAPTER IS AVAILABLE FROM THE CARBURETOR MANUFACTURER WHERE AFTERMARKET CARBURETORS ARE INSTALLED. 

TO ADJUST THE KICKDOWN ROD: ENGINE NOT RUNNING.
1)    Disconnect the throttle and downshift return springs and disconnect kickdown rod from the  kickdown lever on the throttle lever shaft. 

2)    With the choke fully open and the throttle blocked in the wide open position, rotate downshift lever on the transmission fully counterclockwise by pushing down on the kickdown rod to place it against the throw detent stop (or in other words in the "kicked-down position"). 

3)    Turn the adjusting screw on the carburetor kickdown lever to obtain a clearance of .040" to .080" between the throttle lever and the kickdown lever when the rod bushing hole lines up with the lever mounting stud. Reconnect kickdown rod to lever and install *E* clip retainer on the stud. Assure that there is no interference between the rod and other parts of the car that could impede its proper operation.

Refer to this video put out by Holley for an in-depth understanding.