What is the solver step-size that you have selected for your model? The Unit Delay block delays the input by one sample period - so the delay here will depend on the solver step-size.
The Variable Delay block only allows for a maximum delay of upto 10 seconds, since something too large will need a very large buffer (to store previous values).
Could you explain more about why you would like to delay the output for such a large time period? Perhaps we can find another solution.
