Originally Posted by
CPH-Flyer
There is no air side connection between terminals in JFK. I don't know if TSA in T4 would let a passenger pass with a T8 boarding pass, but even if they would I would not take the trek and two TSA visits for a lounge. Where you'd also risk a significant wait as the Delta crowd are quite heavy on the Centurion access.
Soho > Greenwich > Admirals Club is the ranking of the lounges in T8.
Might be questioned at T4 TSA, just tell them you are using the lounge and they will let you in. They are probably more familiar with JetBlue boarding passes. Doable if one has hours to kill, has no checked luggage and has TSA Pre + Clear. But I doubt there is any lounge in T4 superior to SoHo anyway.