His death followed his admission to Pomona Valley Hospital Medical Center about a week earlier for cardiac arrest, according to local news accounts.
Mr. Collins entered the national spotlight with the Mothers of Invention, an outlet for Mr. Zappa's unique sense of humor and challenging, unorthodox compositions. But his musical beginnings were more mainstream.
In the mid-1960s Mr. Collins was singing falsetto in a rhythm-and-blues cover band called the Soul Giants when things soured between him and the band's guitarist, Ray Hunt. Mr. Collins fired Mr. Hunt and replaced him with Mr. Zappa. Precisely how he delivered the news of the firing is unclear.
Mr. Collins "punched his lights out," Mr. Zappa told the television host Mike Douglas in the 1970s. "He was out of the band and they needed somebody to come in and take over for a while, so I went down there and sat in with them and I thought they were real good."
In Mr. Collins's version of the events he threw no punches, but Mr. Zappa did indeed take over the band. Mr. Zappa urged his band mates to perform original material his own and the Soul Giants changed their name, first to the Mothers and later to the Mothers of Invention. The shift in direction eventually led to recognition, a recording contract, some truly original music and a devoted following, if not rock stardom.
Mr. Collins, who shared a love for doo-wop with Mr. Zappa, was the lead singer for the band's debut album, "Freak Out!" (1966), which mixed satirical lyrics with music that ranged from straightforward rock to atonal experimentation, and its follow-up, "Absolutely Free" (1967). He quit the band after that recording, though he returned for "Cruising With Ruben & the Jets," a doo-wop concept album, and sang on some of Mr. Zappa's later recordings.
He told The Inland Valley Daily Bulletin in 2009 that he had grown tired of Mr. Zappa's emphasis on satire. "I wanted to make beautiful music," he said. "I was raised on Johnny Mathis and Nat King Cole."
Mr. Zappa died of prostate cancer in 1993.
Mr. Collins grew up in Pomona and sang in the choir at Emerson Junior High. He met Mr. Zappa in about 1961 after seeing him perform at the Sportsman Tavern in Pomona. The two of them recorded a spoof love song, "Hey Nelda," in 1963 as Ned & Nelda.
The Daily Bulletin said Mr. Collins had been living out of a van in recent years in Claremont, Calif., where he was a familiar sight on sidewalk benches. He told the newspaper he had driven a taxi in Los Angeles for a while and washed dishes in Hawaii. He said he received Social Security checks and some royalties from "Memories of El Monte," a ballad based on the chords for "Earth Angel" that he and Mr. Zappa wrote. The Penguins, the group that made "Earth Angel" a hit, released it as a single in 1963.