I started travelling on the Central line at Oxford Circus at 10:42, and after visiting West Ruislip and Ealing Broadway in the west
and Woodford and Epping in the (north) east
got back to Oxford Circus at 16:42. (That included time for a sandwich and a bit of shopping in Woodford.) From West Ruislip to Roding Valley, the stop a couple of minutes before Woodford, the journey time is 87 continuous minutes; straight to Epping, it's 81 minutes.