I can not tell for sure about the John Summers you are looking for.There is a John Summers in the Morris Summers family in 1880 that is about the right age for yours, but nothing to verify that this is the same person.
John Summers and Flora are still living in 1930 in Indianapolis.They might have death certificates that might give their parents names.
Their marriage records in Marion Co., IN might also give that information if they are available.
About Flora - The marriage index lists her name as Illing, rather than Tilling.There was an Augustus and Maria (Mary) Illing in Evansville, IN who had a daughter married to a John Summers in Indianapolis.This I learned from the Browning Funeral Home Database available on the Evansville Vanderburg Public Library page. The Augustus Illing family came to the U.S. after 1878, but before Flora's birth in 1880.
I am not related to this family.Hope you can use this information.