Unlike the sports fans who attend the 1984 Olympics in Los Angeles, spectators at the ninth Pan American games opening here Sunday need not mortgage the family jewels for the price of a ticket.

The 14,000 persons who already have purchased all available tickets for Sunday's opening ceremonies paid only 20 bolivares, or about $1.50 at the most favorable exchange rate. The closing ceremony on Aug. 29 bears the same tariff, a long way from the $200 top price for the opening and closing ceremonies of the Olympics.

Most events here, including all track and field competition, are free, in accordance with statements made by Venezuelan officials who successfully sought the games four years ago. At that time, they said they wished to have a popular games that even the poorest could attend, as a memorial to Simon Bolivar, the great liberator, whose 200th birthday is being celebrated this year. The only exceptions to the free admission rule are the finals in soccer, baseball, volleyball, boxing and basketball. Tickets to those events cost the equivalent of 75 cents, a continent away from the $95 tariff for the major Los Angeles finals.

Prices here are even less than those for the 1971 Pan American Games in Cali, Colombia, when overflow crowds attended all sports at $2 and $1 fees.

Although disputes between the Venezuelan government and the Venezuelan Olympic Committee have left many preparations to the last minute, including completion of the track and athletes' quarters, enthusiasm is building here for the competition.

Most Venezuelans seem willing to go out of their way to accommodate visitors from the north. There are reasons other than simple hospitality. The floating of the bolivar, which has lost about 75 percent of its exchange value in two years, has enabled Venezuela to compete favorably with other Caribbean resort areas for the first time. Tourism officials are hoping that visitors returning home after the games will spread favorable words about their reception in Venezuela.

The push to complete the athletes' quarters at nearby Guarenas has produced some difficulties, but on the whole everyone is accepting the situation with aplomb. "Trying to finish the village at the same time people are living here has created some problems, but it's nothing we can't live with," said Harvey Schiller, manager of the U.S. boxing team.

"The water and electricity are on until bedtime, then they're off for a while while they work on it. But all nations have the same problems. The big thing here is that the food is superb. That stops a lot of complaining."

The U.S. men occupy 10 floors of building No. 2 at the Guarenas complex, while the women in building No. 3 occupy four floors. The entire U.S. team is staying at the village, although United States Olympic Committee officials apparently are not aware of it.

A U.S. official told a Caracas reporter that the U.S. boxers were staying in a downtown hotel and he was not aware of their training site. A few minutes later, Schiller arrived with the news that the boxers had spent the previous night at the village and were working out at a site only a five-minute ride from their quarters.

The U.S. is having problems other than mere matters of location. Chris Mullin of St. John's, one of the top basketball players, broke his ankle in a game in Puerto Rico and will not participate. It was also considered too late to obtain a replacement.

The boxing team will be represented in only 11 of the 12 weight classes. Michael Grogan, 165 pounds, was declared medically unfit because of a back problem. Alternate Virgil Hill declined to replace him, since he stopped training after losing to Grogan in a boxoff in St. Louis a week ago.

The Cuban team, expected to be the strongest competition for the U.S., arrived without Teofilo Stevenson, the two-time Pan American heavyweight champion. He withdrew after reportedly being beaten badly by a Soviet in Havana.