Olympians Jim Heiring, Dan O'Connor and Carl Schuler are expected to compete with record-holding defending champion Tim Lewis in the U.S. 1985 National Racewalk Championships beginning at Constitution Avenue and Seventh Street NW at 8:30 this morning.

The men will use a 25-kilometer (15.5-mile) course. The women will go 20 kilometers (12.4 miles).

Here in 1983, Heiring, now 29, of Colorado Springs, set a national 25-K record of 1 hour 50 minutes 37 seconds. Lewis, 22, of Boulder, Colo., lowered it last year to 1:49:36.

Schuler, a Silver Spring native, recorded the fastest U.S. time in an Olympic 50-kilometer last summer.

Numerous national racewalk champions will be competing, including Washington's Alan Price, The Athletics Congress 100-mile and 100-kilometer winner in 1984, and Arlington's Sal Corrallo, masters champion at distances from 10 to 50 kilometers.

Among the women, Teresa Vaill of Pine Plains, N.Y., will be defending the 1984 title. Vaill, 22, was runner-up with the same time (1:50:28) as winner Susan Liers-West in 1983.

In Rockville today, more than 3,000 runners are expected for the third annual Fritzbe's 10-Kilometer race. The 6.2-mile run will begin at 8 a.m. on Rockville Pike, across from Congressional Plaza.