The National Football League finished up its 1981 draft in record time yesterday as the 28 teams stockpiled players considered longshots to stick in the professional league.

New Orleans opened the second day of drafting by selecting wide receiver Kevin Williams of Southern California as the first pick on the seventh round. Baltimore took Clemson kicker Obed Ariri on the same round. Ariri, whose 63 career field goals set the NCAA record, last season led the nation with 23 field goals.

The final player selected was Phil Nelson, a tight end from Delaware, who was picked by Oakland.

The draft took 16 hours 19 minutes, making it the fastest draft since the American and National Football Leagues merged in 1967.

The most entertaining round yesterday was the ninth, which gave NFL fans some interesting names to ponder. Toussaint L'Ouverture Tyler, a fullback from Washington, went to New Orleans; Admiral Dewey Larry, a defensive back from Nevada-Las Vegas, went to the New York Jets; Stump Mitchell, a running back from The Citadel, went to St. Louis, and Washington State quarterback Samoa Samoa went to Cincinnati, where he will join his Cougar predecessor, Jack Thompson, the quarterback called the "throwin' Smaoan".

Twelve players from the University of Pittsburg were drafted, more than from any other college. Southern California had nine players selected while Penn State, Ohio State and Oklahoma each had eight picked. Brigham Young, USLA, Nebraska and Missouri each had seven.

Pacific-10 players were the most popular; 42 were chosen. The Big Eight had 32 picked, the Southwest Conference 24, the Western Athletic Conference 19, Southeastern 18, Atlantic Coast Conference 17 and the Big Ten 12.