Olympics could be too much of a good thing in L.A.

When some 600,000 out-of-town sports fans descend on southern California next summer for the Olympic Games, it could be the best of times - or the worst, say area merchants.

One thing is for sure: It won't be business as usual.

On one hand, the games will be directly responsible for at least $3.3 billion spent in the local economy.

On the other hand, the crowds may be too much of a good thing.

Speculation on the horrors of freeway traffic during the 16 days of the games , and the dearth of hotel space, have businesses concerned that travelers are being frightened away and ordinary workdays will be disrupted.

To brace themselves against throttled traffic, some downtown companies are already planning to run deliveries at night. Others will stagger work hours and vacation schedules, or simply be lenient on late workers.

''I think this is going to be a little like Las Vegas,'' says Gil Jacobi of Los Angeles' Merchants and Manufacturers Association. ''It will be a round-the-clock city.''

Mr. Jacobi is trying to make sure businesses aren't taken by surprise. He has formed a task force and scheduled seminars on Olympic planning to help spread the word.

The Los Angeles Olympic Organizing Committee (LAOOC) has the gargantuan task of putting on the games and making sure the travelers who come to watch them can be accommodated.

But Jacobi says the ''average Joes'' - the city's bank clerks, shopkeepers, and managers who need to get to work and make deliveries - need to be prepared for the tough situations that one hopes won't occur.

The chief problem for area residents will be traffic. It will be about 10 percent heavier during the Olympics, according to the California Department of Transportation (Caltrans). But it will be lumped at certain places and times, particularly in the downtown area on Aug. 3, when several events take place.

But if enough people ride buses to major events, traffic flow won't be a serious problem, Caltrans spokesmen say.

Right now, southern California's tourist industry is a little unsure about its Olympic prospects. While virtually all hotels in and around Los Angeles have long been booked for the games (the LAOOC itself has booked 20,000 rooms in the area for officials and sponsors), hoteliers fear that much of their regular business may stay away during the months surrounding the games.

Disneyland hasn't made its forecasts yet, but Michael Bagnall, Disney Productions executive vice-president for finance, is only faintly optimistic. ''On balance,'' he says, ''(the Olympics) will probably bring more tourists into the area.''

Overall the games are undoubtedly a windfall. Using the 1976 Montreal games as a model, David Wilcox of Economic Research Associates estimated last fall that the Olympics would bring $3.3 million into the region.

Without having done further research, he guesses that the figure could be inflated 25 percent and still be conservative.

And it doesn't include the amount that will be spent by all those tourists who will stay a few days beyond their Olympic stay to visit beaches, Disneyland, San Diego, or Santa Barbara.

California economists expect more than $40 million in state tax revenue, plus some $18 million for the City of Los Angeles.

Downtown firms are beginning to map out strategies for coping with the Olympic hordes. Some, like Security Pacific National Bank, have been at it for almost a year.

With 50 branches in Olympic venue areas, the bank is preparing for the best and the worst. It has training manuals available to help tellers identify foreign currencies, both to serve the multitude of foreign tourists efficiently and to protect itself.

It is also studying flexible time plans for employees, coordinated with the schedule of Olympic events. The cash deliveries that each branch needs every day will be scheduled at night or during daytime lulls in traffic while events are actually under way.

''I guess what we've been doing is playing 'What if?' '' says Bill Fisher, a former vice-president at the bank brought back to head the Olympic planning effort.