Montañez first gained fame as a member of the internationally successful El Gran Combo group, with songs like "Hojas blancas" (White Leaves), "Un verano en N.Y." (A Summer at NY), "El barbero loco" (The Crazy Barber), "Julia", "Ponme el alcoholado, Juana" (Rub Me With Alcohol), "Vagabundo" (Bum), "El Swing", etc. He stayed for approximately 15 years, producing 37 LP's. He left El Gran Combo to pursue a career with Venezuelan group La Dimension Latina. Creating a feud between the two groups. After leaving El Gran Combo, he enjoyed considerable success on an international scale with his own orchestra, touring Latin America and the United States several times. He represented Puerto Rico at the 1992 World's Fair in Seville, Spain.