At JFK you can opt out of the radar separation and insist on the 2 minutes for a medium after a heavy.
But it needs to be announced ahead of taxi and you probably get put in line behind another medium where it's not an issue.
If you announce it as you are told to line up or take off you will find the controllers annoyed if there is any kind of traffic going on.
edit: oh and at JFK they are using a new system too as far as i know as part of FAA recat(egorization) effort
so if it's a 767 and not a 747 you might get 4 miles instead of 5 and so on.
Last edited by wiedehopf; 21st Mar 2018 at 10:16.