Camp died Sunday after falling outside his home but the cause has not been determined, the Los Angeles Times reported Wednesday.
Camp and his partner, the late Bob Gibson, were one of the hottest acts in the 1960s and their album, "Live at the Gate of Horn" was one of the era's must-have records, the Times said.
Simon and Garfunkel recorded their "You Can Tell the World," and Peter, Paul & Mary covered "Well, Well, Well."
After breaking up and staying that way for about a decade, the duo reunited and continued to perform together until Gibson's death in 1996.
Camp recorded several solo albums and wrote about 70 songs including "Pride of Man," made famous by Gordon Lightfoot and Quicksilver Messenger Service.
He voiced several of the "Smurfs" for Saturday morning cartoons and appeared in more than 100 films, made-for-TV movies and TV shows. He most recently appeared as a carpenter on ABC's "Desperate Housewives."
His CD, "Sweet Joy," written for his wife of 40 years who died in 2002, is due out in November, the Times said.
Camp is survived by four sons, two daughters and 13 grandchildren.