Upvote:1
If you are taking a cab, there's no problem, three hours is plenty. As per this flyertalk post it's a a ten minute walk from gate to the cab stand if you have no luggage. As per the official page you need at least 30 minutes to get from LGA to JFK. So you have close to two and half hours if using a cab at JFK which is enough even at JFK. Even with traffic jams, this is fine.
It's much hairier with a shuttle as you might need to wait for one and they always move slower. I would personally not risk it.
The gridlock is bad but with the taxi stand moved, it's better.
Upvote:2
Yes, 3:10 is almost always sufficient.
Few points: