There is a piece called the bellcrank that is bolted to the motor. The accelerator linkage moves one end of it. The other end goes to the carb.If these connections are on opposite sides of the pivot point,one goes forward when the other goes back. To make them both move forward at the same time,both have to attack on the same side of the pivot point. The differance in the distance from the pivot is the differance in the ratio of motion(distance) for each.Think about it and make a cardboard template and keep trying.I have a newer motor and had a lot of trouble with emissions "stuff' in the way.