Postitioning of y-axis title

I have what I think is a simple requirement - I want to set where the y axis title will be placed in terms of the value of the y axis. So I would like to do something like include a ‘y’ : 30, for example , in the axis title dict to start the title at y=30.

Reason being I have one plot with 2 y-axes. The left hand axis covers positive values of y, the right hand axis covers negative values of y . I’ve tried setting the range of each y-axis to +ve and negative values only, but that seems to destroy the plot !