I was looking through some transcribed wills yesterday from 1637 and I ran across all kinds of spellings for what we now consider to be the Looney surname. The title sometimes gave one spelling and in the body another spelling was given. Here is some of the spellings (transcribed) that I saw: Lewn, Leawne, Lowny, Lowney, Loone, Leone, Lewne, Leawine, Lewin, Lhawney, Loeney

So from all this it seems that you cannot simply do a text search on a specific spelling of the surname. Granted, Family Search will give you some variations on the spelling of Looney, but those variations definitely do not cover all the possiblilites. If you think the family was in a specific place or parish, you almost have to eyeball scan the document or surname column to see if there are names that sound similar to Looney.