James Ralph Davis, 78, a retired area real estate developer and sales manager, died Saturday at Montgomery General Hospital after a heart attack.

Mr. Davis was a developer and general sales manager with the old Leon Ackerman Realty Company in suburban Maryland from the mid-1950s until 1970. He then joined Tantallon Estates as general sales manager. He worked there until retiring in 1975.

He had lived in Rossmoor Leisure World in Silver Spring for the last five years where he was associated with the Inter-Faith Chapel and was a member of the Kiwanis of Leisure World. Before that, he had been a resident of Bethesda, where he had been a member of the Bethesda Presbyterian Church. He also was a member of the Bethesda Elks Club and was a master Mason in the Bethesda Lodge.

A native of Washington, Mr. Davis was a graduate of Emerson High School. He attended the University of Pennsylvania, then returned to Washington and worked in advertising from 1923 to 1925. He later was in advertising and sales in Florida, North Carolina and New York. During World War II, he worked for an aircraft manufacturer.

After the war, he returned to Washington and worked for the Kaiser-Frazier Corp. before entering the real estate business.

Survivors include his wife of 53 years, Lillian Logan (Dixie) Davis of Silver Spring; two daughters, Dixie D. Porter and Mary D. Barber, both of Rockville; four grandchildren, and one great-grandchild.