Which flights preclear in Dublin depends on which gates they depart from. The US preclearance facility is in the B-terminal/gates, and is fully subscribed. As the number of US bound flights has increased greatly over the years, there are now more flights than can be accommodated in the facility. So, the answer can be found by checking which gates your flight departs from - if B-gate then yes, if not, no. Of course you should also be able to get the answer even more simply by asking EI....