The rat pack walked off with the gold today as United States rowers won four events and placed second in three others at the Pan American Games.

The excellent U.S. showing, which also included a pair of bronze medals and only one shutout on the 10-event program, was in contrast to the 1979 disaster at San Juan, when only the eight-man crew succeeded.

The eight, made up entirely of the lower echelon from the U.S. Rowing Association camp at Madison, Wis.--self-labeled the rat pack--won easily today over Chile and Canada. The four with coxswain beat Brazil by a couple of inches in a thrilling race for the other men's gold.

Women rowed in the Pan Am Games for the first time and the United States captured both events, Chris Ernst breezing in the single sculls and Ann Marsden and Monica Havelka winning the doubles.

In Caracas, diver Greg Louganis won his second gold medal of the games, winning the platform competition, and Rick Carey set a world record of 55.19 seconds in the 100-meter backstroke as the U.S. swimming team added five golds to its haul (story on Page D2).

The United States added three more gold medals in shooting, two in women's gymnastics and one each in equestrian, cycling and Greco-Roman wrestling to run its total to 82 gold medals in seven days. The U.S. women's basketball team continued unbeaten by besting Canada, 87-79. The biggest smiles adorned the faces of the eight, a group composed of two fours and embroiled in a summerlong feud with the U.S. Rowing Association.

The bow oar for the eight was Navy Lt. Dan Lyons, a 1981 Annapolis graduate who stroked the 1980 Naval Academy eight that won the Intercollegiate Rowing Association title. At No. 3 was Paul Jacobson, a 1980 Cornell graduate from Hamilton in Loudoun County, Va.

Lyons and Jacobson were members of the U.S. four without coxswain that won the petite final in the World Championships in Switzerland a year ago, for an overall seventh-place finish.

This year they were on rival fours with coxswain in the World Championship trials, Lyons' boat placing second and Jacobson's third. They were supposed to compete in fours at the Pan Am trials but became angered by the USRA's constantly changing policies and instead combined in an eight that whipped the pre-elite eight the USRA wanted to send here.

"When we went to the camp in Wisconsin, it was supposed to produce the eight for the World Championships, the fours without coxswain for the worlds and the four with coxswain for the Pan Am Games, and all were supposed to be unchallengeable," Lyons explained. "Then they said the Pan Am four had to go through a trial situation.

"As a result, we felt we had no obligation to compete in the fours. One day we were tired of the fours and took a spin in an eight. The world eight, which was preselected, wanted to row some short pieces and we took them on and won three of four; we did it again the next day and the last day we split two of three, with one even.

"When we lost the world trials in fours, we decided to combine in an eight for the Pan Am Games. They tried to legislate us out of it, but we were persistent and we wound up beating the pre-elite eight by five seconds in a course record."

The World Championships open in eight days in Duisberg, West Germany, so in effect the United States was performing well here with a second-string unit. The rat pack does not consider itself in that light, however.

"I'd rather be in Duisberg, but we've had a great time here," Jacobson said. "I'm sure we're having more fun than the world eight. I hear they're having a lot of problems."

The U.S. rowers had some problems here, but this is a resourceful group of athletes. For instance, when the water system was inoperative at the Pan American village, single sculler Ernst, a plumber's helper, traced the pipes and showed the plumbers exactly what to do when they finally appeared.

"I fixed one thing myself and I probably could have done it all if I'd had my tools," Ernst said. "Once we got hot water, it was like living at the Hilton . . ."