Ed Garvey, executive director of the National Football League Players Association, predicted yesterday that rank-and-file union members will refuse to ratify a tentative contract settlement reached Tuesday with negotiators for the NFL.

Garvey said he based his prediction on conversations with union player representatives from the NFL's 28 teams.

Union members had been scheduled to vote on the proposal next Tuesday. But Garvey said it is unlikely a draft of the proposed settlement will be ready for submission to the players then. He said it would be more likely that a vote would come later in the week.

In the balloting, Garvey said, players will probably be given a choice of voting to accept, reject with the option of continuing to play, or going back out on strike.

But he said yesterday there still are issues unresolved in the tentative agreement, and that the package will not be submitted to the general membership until all details are cleared up. Among the unresolved issues, he said, are the number of games to be played next year, whether a player has the right to bring a lawsuit against the NFL and the length of the agreement between the league and the union on the college draft.

"These are substantive issues that have to be dealt with before we can submit this to the players," Garvey said. "I don't think anything is irresolvable. I think they can be solved."

Jack Donlan, the executive director of the NFL Management Council, the league's labor negotiating arm, said the council's executive committee would decide whether to let players continue the season without a ratified contract. He would not predict what decision it might make.

Donlan also disagreed with Garvey's prediction that the offer would be voted down. "I think there is a lot of support for the offer," he said.

If the players vote against ratification of the contract, Donlan said, the NFL will withhold $60 million in bonus payments to current players that it promised effective with the signing of the contract. There also would be other reductions, he said.

"The whole purpose of that offer was to get a settlement so we would have labor peace," Donlan said.

Yesterday, lawyers for both sides continued the painstaking process of refining language in the settlement agreement and then initialing each page. The offer guarantees $1.28 billion in player costs for 1983-1986, and includes a minimum wage scale and -- for the first time in the NFL -- severance pay upon retirement. This year's package is the face value of the individual player contract -- minus pay for games lost because of the strike -- plus the bonuses and improvements in playoff and Super Bowl benefits.

Since voting to approve the agreement, 19-6, with one abstention in New York (two player representatives were absent), player representatives have returned to their teams, where they have been discussing the tentative accord with teammates.

Garvey said many union members are unhappy that the negotiated minimum wage scale is not higher. Negotiated minimums for rookies are $30,000 this year; $40,000 in 1983 and 1984 and $50,000 in 1985 and 1986. Those sums increase with each year in the NFL, but they are still lower than average salaries in the league.

Garvey said members of the New England Patriots had voted against the proposed settlement, 38-1, in a straw vote held on Thursday. The Patriots reportedly had threatened not to play Sunday against the Cleveland Browns, but agreed to play after meeting with Garvey for 3 1/2 hours Thursday night.

Garvey also said it is not certain that players will vote in secret ballot on the ratification issue. "I don't think we've ever had a secret ballot," he said. Some of the union's player representatives, he said, believe union members should be accountable for their votes. He said the player representatives will decide if ratification will be by secret ballot when they meet here Monday or Tuesday of next week.

Donlan contended open voting would give union members a chance to pressure others on how to vote. "I think it's important that they have a secret ballot," Donlan said.

In other matters, Garvey admitted the union is heavily in debt, but he said that had no bearing on Tuesday's tentative settlement ending the 57-day strike. He also said a merger with another union had been considered if the 1982 season was canceled. But he denied a report in yesterday's editions of The Washington Post that there was any consideration given to merging with the Teamsters.

In other strike-related developments, Elvin Bethea, the player representative of the Houston Oilers, said yesterday he is opposed to the tentative settlement and plans to resign from the executive committee of the NFLPA.

"I don't think the agreement is in the best interest of the players today or the players of the future," the Associated Press quoted Bethea as saying in Houston. Bethea is planning to retire at the end of the season.

In Pittsburgh, Dan Rooney, president of the Pittsburgh Steelers, said he felt Garvey had done a good job of representing the players' interests, according to United Press International.

"This is a tremendous thing for the union," said Rooney. "They got the wage scale and a situation where they have control of agents. Every one of their football players isn't happy about it. But this is a new concept."