Strong Field for Speedway Nationals : Motorcycle racing: World champion Ermolenko joins six riders who have won U.S. titles.

The strongest field ever assembled for the United States National Speedway motorcycle championships--headed by world champion Sam Ermolenko of Cypress and defending national champion Chris Manchester of Hesperia--will compete tonight at the Orange County Fairgrounds.

Manchester tuned up for his defense by winning the California State championship with a perfect 15-point total last Saturday at Glen Helen Park in San Bernardino.

Ermolenko recently became the third American to win a world individual title, but he has never won the U.S. crown. Other American world champions were Jack Milne of Pasadena (1939) and Bruce Penhall of Balboa (1981-82).

Manchester made history last year when he became the first rider to win the national championship in his first attempt, and at 19 is the youngest national champion. He also did it by scoring a perfect 15--the first time it had been done in the nationals since Penhall in 1980.

Five others who won national championships have qualified for tonight’s 16-rider field. They are Alan Christian (1985) of Reno, Bobby Schwartz (1986 and 1989) of Costa Mesa, Brad Oxley (1987) of San Juan Capistrano, Steve Lucero (1988) of Riverside and Mike Faria (1990 and 1991) of Apple Valley.

Faria finished one point behind Manchester in the State finals.

Another favorite is Monrovia’s Billy Hamill, who has been riding in Europe and, with Ermolenko, was a member of the winning U.S. team in the World Speedway Cup two weeks ago in England.

Only one rookie rider, John Aden of Apple Valley, survived qualifying races to advance to the final. Other riders tonight include Gary Hicks of Riverside, Robert Pfetzing of Orange, Brent Werner of Hesperia, Lance King of Fountain Valley, Charlie Venegas of Newport Beach, Jim Sismore of Woodland and Billy Bast of Auburn.

The first of 20 heats, in which every rider faces every other rider once in a series of four-lap races, will start at 8 p.m.