Something is up in pro football. Billy Kilmer doesn't know what it is, but he thinks it is big. He has talked to George Allen, and he thinks George will be a top dog in something called the United States Football League. George will own and/or coach the Los Angeles team. This is what Billy Kilmer says. George told The Post recently there is nothing to it.

"It's kind of suicide to go after the NFL," Kilmer said offhandedly near the end of a phone interview about his league, the American Football Association. Kilmer is the commissioner of the AFA, a 10-team pro league operating in the spring and summer with a championship game scheduled for Aug. 29.

Suicide, Billy? The AFA pays its players 1 percent of the gate. The teams are in Dallas and Shreveport, Chicago and Roanoke, Orlando and Austin, Charleston (w.Va.) and San Antonio, Jacksonsville and Charolotte. This doesn't sound like a league going head-on with the NFL. What's this about suicide?

"I'm talking about the George Allen league," Kilmer said. "They're going a little bigger than us."

The guy taking nice, not-very-newsy notes woke up about here.

A George Allen league?

The old Redskin quarterback said his old coach is involved in what is yet only a concept.Kilmer named Tornoto millionaire John Bassett, late of the went-broke-fast World Football League, as "just a piker in this thing. There is a lot of money behind them. They want to play in the spring and summer, and they want to go after the NFL. Mainly, they'll go after No. 1 draft choices."

Here we pause for a disclaimer. There is, dear reader, the very good chance that Commissioner Kilmer is seeing bogeymen in the shadows who would eat alive his little league. For while Kilmer speaks of a USFL full of men with money to burn, other football people pass off this league as simply another hustler's con game, this one designed for sale to the cable TV people who need sports 24 hours a day, 365 days a year.

But Kilmer's musings are fascinating, anyway, especially when he plots a scenario explaining how a USFL could be born.

The only way (Kilmer says) big-money people would get involved in yet another league is for them to have assurances that top players would be available. So Commissioner Kilmer, over the phone, asked a good question, "How would the backers get those assurances?"

Through Ed Garvey? With the baseball strike fresh in a newspaperman's labor union leader pops up quickly. The National Football League Players Association, of which Garvey is executive director, and the NFL owners must sign a new contract before the 1982 season. And if the football owners then are as foolishly stubborn as the baseball people are now, there will be a football strike.

Does Kilmer believe Garvey is telling the United States Football League investors that there will be a players' revolt against the NFL?

"It ain't too hard to figure out," the commissioner said. "Garvey's in trouble with his own union, as everybody knows, and he could be thrown out. But if he wins the fight for control, then look out."

Well, yes, Ed Garvey said yesterday, he knows about the United States Football League.

Not only knows about it, but loves the idea of more teams competing for players and so driving up salaries, which are far below the averages of baseball and basketball wages.

"I certainly would like another league," said Garvey, who is held responsible by some NFL players for not securing the workable free-agent plan that has made made wealthy their baseball and basketball contemporaries.

Garvey added he didn't know any of the USFL investors by name, which is a nifty way to deny Kilmer's scenario, but said, "It's not a World Football League situation, where the league is underfinanced. These are all very substantial individuals."

The USFL would be "more interested in rookies" than in pirating away established NFL stars, Garvey said.

"The United States Football League draft would be well in advance of the NFL draft, maybe by seven months," Garvey said. "They could offer a draft choice the possibility of playing in their spring-summer league and then playing in the NFL, too, before going back to school. Rather than a lot of money, the rookies would get a chance to play with respectable teams with first-rate coaches."

There might be some NFL players available, too, Garvey said.

"Those who play out their option this year will be free agents by Feb. 1," he said. "There might be 100 or 120 of them. They will give the USFL a pretty good head start. And a lot more than that might play out their option in anticipation of a new contract with the league. The current system is a joke."

The current owner-player relationship is, indeed, a joke. Pro football players are the last slaves in pro sports. Garvey says the Los Angeles Rams took in $18.4 million in revenues last season while paying their players $4.2 million. That's 23 percent to be hired hands. Garvey says the baseball players get 40 percent of all revenue; hockey players get 48 percent, and basketball players 60 percent.

"Football players get about 28 percent right now," Garvey said, "and in the new contract we'll ask for 55 percent."

But we digress. Our subject today is Billy Kilmer. Before he so nicely interrupted our casual conversation with a piece of irresistible speculation, the commissioner said he was having fun at his new job. He said the caliber of play in the AFA is surprisingly good, largely because so many good college players miss out on the NFL as victims of circumstance. The biggest AFA crowd in three weeks so far has been the 7,835 seeing Jacksonville at Orlando. A TV deal that fell through may be revived as a four-game package including the championship game.

Kilmer's race horses are doing fine (three runners, two broodmares now). His golf game is coming along. He has changed his mind now about ever wanting to coach in the NFL. He'd like to be a front-office type, now that he has seen he could handle the political and diplomatic demands of the job.

"I have," said the commissioner, who watched damply as a thunderstorm reduced an expected 20,000 crowd to 4,425 at Shreveport two weeks ago, "new respect for Pete Rozelle."