I have been plowing recently but the 3 p.h. lift does not seem to lift high enough.  The tail of the 4 bottom, 3 p.h. plow often catches on the sod of the headlands (or the crown of the paved road) I think there must be some sort of adjustment to make the lift arms of the tractor raise higher. Attached to  the lift lever there is what appears to be a linkage adjustment, a  small threaded rod about 3/32 in. diameter and has a jamb nut . Will lengthening this make the lift go a little higher? I am also assuming this can be over-adjusted. How much is safe? Any comments are welcome.
    Thanks,
              Cal