Starting in 1916 a rebuilding program converted ninety class E2a, b, and c to class E7s by replacing slide valves with piston valves and increasing cylinder diameter from 20.5 to 22.5 inches (520 to 570 mm).

These improvements allowed many of the engines to remain in active service into the 1930s.

The sub-classes differed as follows:[2][page needed] In the first decade of the twentieth century classes E2 and E3 handled all of the fast passenger trains of the Pennsylvania Railroad.

On the first westward run of the Pennsylvania Special (renamed the Broadway Limited in 1912) in June 1905 the conductor clocked the train over three miles just west of Lima, Ohio in 85 seconds, at a record speed of 127.1 miles per hour (204.5 km/h) (the claim is dubious, as the train averaged about 68 mph (109 km/h) from Crestline to Fort Wayne).

The engine was donated to Railroad Museum of Pennsylvania in 1979 and put into operating order by Strasburg Rail Road where it ran for until December 20, 1989, sometimes doubleheading with PRR D16 No.