The Senate voted 70 to 27 yesterday to limit debate on the administration's plan to sell Conrail to Norfolk Southern Corp., thus assuring that the contentious issue finally will move to the House.

That margin is 10 votes higher than required for cloture and guaranteed the failure of Norfolk Southern's opponents to succeed in the Senate.

After an afternoon of debate and delay following the cloture vote, Majority Leader Robert J. Dole (R-Kan.) said the Senate will adjourn today and take up Conrail again Tuesday. "Although I have no agreement, I have the word of a number of senators that we will conclude on Tuesday," Dole said.

His announcement came after a whispered meeting on the Senate floor with, among others, Sen. Howard M. Metzenbaum (D-Ohio), who has been the most vigorous opponent of the Conrail sale and had incurred the wrath of several colleagues by continuing the debate yesterday. Many senators were anxious for adjournment last night so they could attend the memorial service in Houston today for the seven astronauts killed in Tuesday's space shuttle explosion.

"It's over" in the Senate, one of the Transportation Department's senior officials said. Top DOT officials, along with Norfolk Southern's team of lobbyists, spent the day patrolling Senate hallways to make sure they had their votes in order.

In a series of roll-call votes that started Wednesday, the Senate defeated one amendment after another to legislation originally passed by the Senate Commerce Committee. It calls for the sale of the federal government's 85 percent share in Conrail to Norfolk Southern for $1.2 billion.

Among the amendments defeated was one that would have replaced Norfolk Southern as the purchaser with an investor group organized by Morgan Stanley & Co. That failed, 53 to 39. Thomas A. Saunders III, managing director at Morgan Stanley, nonetheless claimed victory.

"For us, to lose by 14 votes . . . gives us a tremendous base for a swing to the House," Saunders said. He reiterated that the Morgan Stanley offer is valid through June and said his investors remained enthusiastic.

That was before the cloture vote, however, which was heavier for the administration than even Norfolk Southern's strongest adherents were predicting.

The margin was aided somewhat when the Transportation Department agreed to a last-minute amendment from Sen. Larry Pressler (R-S.D.) who, along with others, has been concerned about possible anticompetitive consequences of a merger of Norfolk Southern and Conrail and was considered a threat to join a filibuster.

The amendment, which passed on a voice vote, provides for Interstate Commerce Commission review of pricing practices by Norfolk Southern/Conrail if there are freight diversions of more than 3.5 percent from four midwestern railroads, the Grand Trunk Western, the Illinois Central Gulf, the Chicago and North Western and the Soo Line.

Norfolk Southern officials were slightly unhappy about the amendment, although delighted about things in general. Edward T. Breathitt Jr., Norfolk Southern's senior vice president for public affairs, said "we just got rolled" on the amendment. What he wanted from the four railroads in exchange for an antidiversion guarantee was their explicit support, which he did not get. However, he said, "their opposition is considerably weakened."

Breathitt said that, because of the Pressler amendment, "a whole lot of people we haven't been able to get were for us" on the cloture vote.

Senate rules permit 100 hours of discussion after cloture is voted. Metzenbaum had filed more than 100 amendments, thus assuring there was plenty to debate. Quorum calls and roll calls do not count against the time limit.

Before his early-evening meeting with Metzenbaum, Dole had threatened to keep the Senate in session through today so action could be completed this week.

After the first of Metzenbaum's post-cloture amendments went down, 70 to 26, Sen. Barry Goldwater (R-Ariz.) called the continuation of the issue "an abuse by a few people." He suggested that Dole should have called the final vote at one point during the afternoon when opponents to the Norfolk Southern purchase were absent. "If they don't get here," Goldwater said, "to hell with them."