My 66 inline 6 feels like it has a stiff pedal when running. It takes some force to push it and once it moves it takes off making for a very jumpy ride (3 spd manual). Its very hard to be sensitive with the pedal. I have a theory that it is due to the angle in which the throttle link meets the throttle lever (pic included). It seems to be an almost straight angle which gives it no leverage so it has to fight to rotate it, and once it gets far enough the force needed lessens so it jumps.
Is...
66 i6 throttle link setup/angle