It is still uncertain whether the $500,000 U.S. Grand Prix will be run Oct. 5 at Watkins Glen, N.Y., its home the past 21 years.

Event director Mal Currie said in a phone interview that an unfavorable report would be filed by inspectors who toured the 3.3-mile track Thursday and Friday to check on safety improvements required by the International Federation of Automobile Sport (FISA).

"Mr. (Maurice) Belien, the chief inspector, told me he felt that even with the repairs we are making, he would not consider the track safe. He has sent his report to FISA. We assume Mr. (Jean-Marie) Balestre, the FISA president, will make the final decision early next week."

Earlier this year, FISA told the Glen to make improvements in the tracks surface and buildings or lose the race. Rejected for a federal loan guarantee guarantee, the Glen did get $200,000 from a private group a few weeks ago to allow the most urgent work to begin.

"We started late because we didn't have any money," said Currie. "The work is going on. I don't agree the track would be unsafe once we finish." The work includes repaving about 25 percent of the track surface, admittedly rough for the fragile Grand Prix cars, revamping the guard rails and improving press and driver working conditions and amenities.

David G. Schlosser, Rochester, N.Y., investment counselor and amateur racer who raised the $200,000, is now trying to raise another half-million dollars. This total would permit all improvements to be made and would trigger release of some state-controlled funds to the Glen.

A final inspection has been scheduled for Sept. 28. This may be unnecessary if the race is canceled. The car owners probably would not be too happy over a cancellation since they will be at the Canadian Grand Prix then and would lose the Glen's expense and purse money.