Stepper/time equation problem

Hi, I have an equation that I have been staring at for hours. Hope this is in the right section, it's a weird one.
i have a stepper motor attached to a clock to essentially have my clock run at the wrong time. I am trying to come up with a formula to calculate the delay needed to get certain time ranges.

The way it is currently set up the clock takes 4 mins 14 seconds 'real time' to run 60 mins of 'clock time' with the pulse delay set to 1000ms. Every time I send a pulse the clock moves an increment.

I am trying to come up with a formula to adjust the pulse delay to get different running times.

In particular I am trying to get the clock to run 1.97 mins CT 'clock time' for every minute of RT 'real time'

I have worked out a formula for working out the delay on 1 minute of clock time that is almost there but I am now a bit stuck.

1000ms delay / 4.25minRT = 235.294
2000ms delay / 8.5minRT= 235.294

So

10minRT x 235.294 = 2353ms delay
2353ms delay = 10mins RT to do 1 min CT

I want to find out the delay to get 1.97mins CT in 1 min RT

Please, no suggestions for changing the clock design/workings. I am stuck with using this method and need to
come up with a formula to match the setup.

Hope this makes some sort of sense. At help appreciated, especially with workings.

Thanks in advance