Despite two years of complaints about preparations for the 1984 Olympics, U.S. officials here say they are convinced the Soviet Union and its East European allies will attend the Games in Los Angeles.

Officials say arrangements announced at last week's meeting of the executive board of the International Olympics Committee, plus the removal of an antagonistic U.S.S.R. Olympics chief and a series of Soviet visits here, indicate Moscow has decided not to retaliate for the U.S. boycott of the 1980 Games in Moscow.

"I think without question they are going to come," said Los Angeles Olympics President Peter V. Ueberroth. He said the Soviets had promised not to use the Games for political purposes, were concerned about the huge Chinese delegation scheduled to attend for the first time and had learned that boycotts "just don't work." Despite African boycotts to oppose apartheid, Ueberroth noted, apartheid still exists in South Africa. Despite the U.S. boycott to protest the Soviet invasion of Afghanistan, he said, Soviet troops remain in that country.

Although the Soviets have until eight weeks before the 1984 summer Games to make up their minds, Olympic Committee Deputy Chairman Victor Ivonin indicated at a press conference here that his delegation sought only some improvements. Ivonin complained of "the intrustion of professionalism and commercialism in these Olympic Games," a common theme since the Los Angeles Olympics will make history by being supported almost entirely by private funds.

At last week's meetings, Ueberroth and IOC officials announced a $35 an athlete a day fee for use of the Olympic villages, lower than the once-projected $45 fee, in response to complaints from the Soviets and many other delegations. Olympics officials also said that the U.S. ban on landings by the Soviet airline Aeroflot, another result of the Afghanistan invasion, would be lifted for planes taking members of the Soviet delegation to the Games. A Soviet cargo ship also would be allowed to dock in Los Angeles harbor.

Los Angeles Olympics officials also promised close attention to security, a common Soviet theme, and demonstrated it with generally tight restrictions on access to meetings of the executive board last week. They said they would meet Soviet and other complaints about heavy summer smog here by scheduling particularly strenuous events, such as the marathon and rowing races, early in the morning or at sites far from the city.

In 1980, Sergei Pavlov, the Soviet sports minister and Olympics chairman, called for a ban on U.S.S.R. participation in the 1984 Games in retaliation for the 1980 boycott. Pavlov has remained a staunch critic of the Los Angeles arrangement, but shortly before last week's meeting it was revealed in Moscow that he had been removed from his sports post and was rumored to be on his way to a diplomatic assignment in Outer Mongolia. Officials in Moscow said he had been replaced by Amarat Gramov.

Los Angeles officials said they had an early clue to a change in the Soviet attitude when a large technical delegation arrived in December and later praised the arrangements they had seen here. Olympics officials here also appeared to impress delegates from 145 countries last week by using a network of volunteers, the beginnings of a planned 10,000-member volunteer organization expected to help conduct the 1984 Games. The delegates also were broken into small groups for dinners at 60 separate private homes in the area, rather than being invited to the traditional gala banquet.

Ueberroth said the Soviets have continued to complain about some arrnagements, but "I don't fault it because it was not a long time ago that our country, by a misguided decision, decided to use athletes for political purposes."