The Republican National Committee, overcoming a minor mutiny in the ranks, yesterday selected Detroit as the site of its 1980 National Convention.

The GOP leaders ratified a selection committee's choice of Detroit over six other cities that had bid for the convention -- but only after a spirited two-hour debate in which they came close to rejecting national chairman Bill Brock's pleas on Detroit's behalf.

The choice means that the Republicans will select their 1980 presidential nominee in one of the nation's strongest Democratic bastions. Some of the convention rallies, in fact, will be held at the "Philip A. Hart Plaza" -- a location near Detroit's Renaissance Center that is named for the late Democratic senator who regularly trounced all Republican challengers.

Brock said that Detroit's political and ethnic profile -- the city's population is about 55 percent blace -- was a strong factor in its selection. He said meeting in Detroit will enhance the GOP's effort to build the image of a party reaching out to minorities and union members, who have traditionally supported Democrats.

But other members of the National Committee, which is meeting this week at the Sheraton Park Hotel, argued that image considerations dictated a choice of New Orieans or Dallas, the cities that seemed to be Detroit's closest competitors for the convention. "We want to show people that we're not giving up the South to Jimmy Carter," said Ray Barnhart, the Texas GOP chairman.

Committee members opposed to Detroit also cited a lack of downtown hotel space and a fear of crime. They said that racial considerations had no bearing on their views. But Clarke Reed, the talkative committeeman from Mississippi, told the Detroit Free Press that "I'm the only white man from Mississippi who's ever been to Detroit. I don't want to be the only white man who ever goes back twice."

Presidential politics also played a role in the debate. Backers of Ronald Reagan, the current favorite to snare the party's nomination in 1980, were pushing for one of the southern cities, on the theory that the South might be more congenial territory than Michigan, where GOP moderates outnumber Reaganites.

But Charles Black, one of Reagan's political braintrusters, said the choice of Detroit would be "no real problem" for the former California governor. "By the time of the convention, we should have won the thing in the primaries," Black said.

Brock said Detroit was preferable to other cities on "technical" grounds. The Cobo Hall arena that will be the main convention hall is just about the right size for the 4,000 delegates and alternates, 4,000 "honored guests," and 10,000 media people expected to attend.

The Dallas hall was considered too small, and the New Orleans Superdome seemed too big -- even though the city offered to hand a $350,000 curtain to cordon off the right amount of space.

Stil, when the selection committee recommended Detroit yesterday, the National Committee members kicked up a fuss that took two hours and three votes to put down.

The key vote came on a motion to choose the convention city by secret ballot -- a procedure that would have made it easier to vote against the recommended site.