American League baseball owners are expected to vote overwhelmingly in favor of a split season when they meet to discuss the issue Thursday, but the National League owners, who would have to approve the split season by a three-quarters vote for the measure to take effect, appear to be more envenly divided.

According to a survey by United Press International, the American League, where only a simply majority is required, is expected to adopt the split season by a 12-2 vote, but the outcome in the National League could go either way.

One veteran National League owner said a discussion last week "produced three or four firm yeses, two very strong nos, a maybe toward the no side and two others riding the fence." He did not account for the remaining votes.

Baseball Commissioner Bowie Kuhn has said both leagues must adopt the same system. Should the American and National leagues vote differently, the matter would go before him for resolution. Kuhn has said certain aspects of the split season appeal to him, but he has not indicated how he would vote.

The owners originally were scheduled to meet yesterday in Chicago, but the strike by the air traffic controllerd forced postponement of that session. If Thursday's meeting, also scheduled for Chicago, has to be postponed the owners will resolve the issues by conference call.

Adoption of the split season would give automatic playoff berths to the four teams in first place in their divisions when the strike began June 12. Second-half winners would play a preliminary playoff with the first-half winners to determine divisional championships. If a team won both halves, the owners have two options on the table: the team could receive a bye into the league playoffs, or, would be forced to meet the team in its division with the next-best overall percentage for the entire season in the preliminary playoff.

White Sox President Eddie Einhorn was seeking support last night for a split-season -- but with a different format. He predicted that his compromise would win the approval of the owners.

Under Einhorn's proposal, the season would be split into two halves with the second-half winner and the team with the best overall record for the entire year advancing to a "miniplayoff."

"It just seems to me you ought to get something for having the best record in your division over the entire season," Einhorn said. "After all, isn't that how we determine the pennant winners every other year?"

In another baseball development yesterday, a lawsuit was filed by a group of fans in U.S. District Court in Cleveland seeking a permanent injunction halting Sunday's All-Star Game. The suit charged the game will be a sham because of the strike and poor physical condition of the players.

San Diego pitcher Juan Eichelberger said he will accept no pay for the Padres' Aug. 10 game against the Atlanta Braves. Eichelberger said he was following the line set by Padres' owner Ray Kroc, who has offered free admission to any fan attending the first game after the strike ends.

And Labor Secretary Raymond Donovan, who played an active role in seeking a solution to the strike, will throw out the first ball Aug. 10 before the Yankees open against the Texas Rangers.