Clarence Adams worked one game as a fill-in umpire on May 22, 1976 at Three Rivers Stadium in Pittsburgh, PA. The vendors at the ballpark were on strike that day, and a number of other unionized personnel decided to join in solidarity, including that game's umpiring crew. Four amateur umpires were quickly rounded up, including Adams, who worked second base, and Joe Puskaric, who was at first base, neither of whom had ever worked a major league game before; the other two, home plate umpire Joe Schratz and Al Cohen at third base had worked the previous day's game, partnering with two other colleagues.
A Federal judge issued a back-to-work order for the striking umpires before the start of the afternoon game between the Chicago Cubs and Pittsburgh Pirates, but it arrived just before game time and Pirates GM Joe Brown told the regular umpires that they were too late and that the fill-ins would work the game. The game turned out to be a 16-inning marathon, won by the Pirates, 4-3, and Adams returned to obscurity afterwards.