Pope John Paul II was installed yesterday in a solemn outdoor ceremony as the 263rd successor to St. Peter as the bishop of Rome and head of the Roman Catholic church.

In the crowd of tens of thousands of government dignitaries and ordinary believers, was a colorful contingent of 3,000 Poles, many of them in national costume, who came to attend the installation of the first Polish pope and the first non-Italian in 455 years. They waved red and white Polish flags.

The pope was repeatedly interrupted by applause, first by the Poles in the crowd and then by the Romans, as he offered a homily in Italian in a strong, clear and highly expressive voice:

"To the See of Peter in Rome there succeeds today a bishop who is not a Roman. Abishop who is a son of Poland. But from this moment he, too, becomes a Roman. Yes, a Roman. He is a Roman also because he is the son of a nation whose history, from its first dawning, and whose thousand-year-old traditions are marked by a living, strong, unbroken and deeply felt link with the See of Peter, a nation which has ever remained faithful to this See of Rome."

John Paul II's ceremony of more than three hours, like that of Pope John Paul I in August was simplified to eliminate the coronation with the three-tiered papal tiara and the use of the portable throne to carry the pope.

The actual installation took just a few moments at the start of the ceremony. Cardinal Pericle Felici, the dean of Vatican deacons, placed the pallium over the new pope's shoulders.

The pallium is a white wool shawl emboridered with black crosses. Since the 6th century, it has been the symbol of the authority of the bishop of TEXT OMITTED FROM SOURCE

After getting the pallium from the hands of the same man who gave it to Pope John Paul I at the start of his 34-day reign the new pope sat on a throne to receive each member of the Sacred College of Cardinals in turn.

Each cardinal came forward to kiss the Pope's ring in a sign of loyalty. The first after Cardinal Carlo Confalonieri, the dean of the College of Cardinals, was Cardinal Stefan Wyszynski, primate of Poland.

The new pope, who, as Cardinal Karol Wojtyla of Krakow, was the second-ranking prelate in Poland, prevented Wyszynski from stooping to kiss his ring. Instead, the Pope rose and kissed the primate's forehead and cheeks. Then, the Pope bent and kissed the primate's ring.

Poles in the audience applauded. Among the crowds that came from Poland by charter plane, train and tour bus was the woman who was Cardinal Wojtyka's housekeeper in Krakow for 18 years. At the end of the ceremony, a Polish priest with red-and-white ribbons pinned to his lapel said in halting English of the pope's installation, "Special occasion for us. Beautiful. We very happy in Warsaw." His mother, whom the priest had brought with him from Warsaw, stood by beaming.

Polish president Henryk Jablonski was the most notable of the official representatives of 102 nations, including the presidents of Austria, Ireland, Italy and Lebanon and the premiers of France and the Netherlands. Royalthy included King Juan Carlos of Spain and Queen Sofia, the grand duke and duchess of Luxembourg, Prince Rainier of Monaco and Princess Grace, and the duke of Norfolk as the representative of the queen of England.

The United States sent a 35-member delegation headed by Sepaker of the House Thomas P. O'Neil Jr. (D-Mass.) and national security adviser Zbigniew Brzezinski, the highest-ranking American of Polish birth in the U.S. executive branch. Others included Sen. Edmund Muskie (D-Maine) and most of the other congressmen of Polish descent, former New York mayor Robert Wagner and John Wojtylo, a cousin of the new pope from Detroit.

Pope John Paul II spoke mostly in Italian, but at the end of his sermon he spoke at least a few words of greeting in 10 other languages - Polish, English, French, Spanish, Portuguese and all the languages of countries and regions neighboring Poland - German, Czechoslovak, Russian, Ukrainian and Lithuanian.

The longest passage was in Polish. It provoked such heavy applause that he had to motion for silence. Addressing himself to "My dear fellow-countrymen, pilgrims from Poland, brother bishops with your magnificent primate at your head," he continued:

"What shall I say? Everything that I could say would fade into insignificance compared with what my heart feels, and your hearts feel, at this moment. So let us leave aside words. Let there remain just great silence before God, the silence that becomes prayer. I ask you, be with me!

He made it clear that he intends to keep working to improve the lot of believers who live in countries like Poland that are officially hostile to religion. In a growingly impassioned tone, the pope said, "Do not be afraid. Open wide the doors for Christ. To his saving power open the boundaries of states, economic and political systems, the vast fields of culture, civilization and development."

The overwhelming impression the 58-year-old pope gave with his strong voice was of youthful vigor. As he chanted while consecrating the Host during the mass, many people could be heard murmuring. "What a beautiful voice."

When he sermonized, he spoke with dramatic emphasis, often pausing and pacing himself for effect. His delivery seemed to owe something to his early training as an actor.

Above all, he seemed to be enjoying himself. If actuarial tables and appearances are any guide, the pope could lead the Rome Catholie Church through the end of the 20th century.

The Vatican press office said that the service was broadcast live by radio and television more widely than any other Vatican transmission - to 47 countries in Europe, North and South America and Australia.

Poland was the only Soviet-bloc country to give live television or radio coverage. It was the first time the Polish government had authorized such a broadcast. Radio Free Europe, the Voice of America and other Western radios retransmitted the services to the communist world.

The pope turned the radio and television into instruments of his ministry. To all those attending the ceremony at the Vatican and to all his radio listeners and televiewers, he granted a full pardon of sins.

The pope displayed an affectionate side to his nature. For each of the cardianls who came up to him, he had a few special words. He often caressed the shoulders of their gold vestments.

Even the Vatican churchmen serving the pope during the service showed special interest when Cardinal Giovanni Benelli of Florence, the presumed leader of the unsuccessful effort to select an Italian pope came up.

Vatican prelates were apparently so interested to hear what was being said that they blocked the television cameras. In the Vatican press theater, reporters spontaneously started shouting for the priests to get out of the way, forgetting in their desire to see that the prelates out on St. Peter's Square could not hear them.

The pope ended the ceremony by leaving the sun-lit square and going up to the window of the papal apartments for which popes traditionally greet people on St. Peter's Square each Sunday. He gave a prayer and held out his arms in blessing and then crossed them over his chest in the hugging gesture that he has made familiar to Romans this week.

Then, he said into the mircrophone in a normal, non-liturgical voice, "It's time to finish up because it's time for lunch, for you, and for the pope."