Isador Santavicca;66;of Arnold City;Belle Vernon;died Friday;Dec.12;1986;at 4:30 a.m.in Mon Valley Hospital;Carroll Twp.;after a lengthy illness.  Friends will be received Saturday and Sunday from 2 to 4 and 7 to 9 p.m.in the Howard W.McCrory Funeral Home;Fayette City. A Prayer Service will be held Monday at 9:30 a.m.in the funeral home;followed by a 10 a.m.Mass of Christian Burial in St.Sebastian Roman Catholic Church;Belle Vernon.  Burial will be in Belle Vernon Cemetery;Belle Vernon.  The Howard W.McCrory Funeral Home is in charge of arrangements.