First of all apologies if this is in the wrong section, I'm planning to fly to EWR from LHR in 4 weeks and the flight I'm interested in has a layover at IAD. The connection time is 70 minutes.

Am I right in thinking this isn't gonna be enough time? I'll be landing at IAD at around 4:40 PM which is a busy time apparantely. Also haven't heard many good things about the immigration at IAD.