The City Council on Monday approved a zone change that would allow housing at the former Mutual Ford car dealership site in the Pine Point neighborhood. Hampden developer Alston Graham, of Graham's Construction Inc., wants to build 23 high-end single-family homes on the long-vacant, blighted property at 1535 Bay St. He purchased the parcel in October for $470,000. Graham requested the zone change from Business B, which allows for a mix of commercial and residential properties, to Residence A, which allows for single-family homes. The council approved the change 10-0 with three councilors absent.