A congressional conference committee agreed yesterday to grant a $1.6 billion federal subsidy to the District of Columbia's financially troubled pension programs, but deadlocked over proposed tighter rules for disability payments to police and fire-fighters.

Racing against a scheduled congressional adjournment date in mid-October, the joint Senate-House panel agreed to meet again Wednesday for what members called a "now-or-never" attempt to reach agreement.

The conferees are attempting to reconcile the House and Senate versions of a bill intended to put the now-unfunded retirement programs for four groups of city workers on an actuarially sound basis, with pension fund income equaling payments to retirees.

At present, the city government owes current and future retirees more than $2 billion in benefits, but has no money set aside to make the payments because Congress decided the city should pay benefits from the city's annual budgets.

By 1984, the pension debt will reach $3.5 billion and, by the turn of the century, it is estimated that payments to pensioners would exceed salaries paid to active workers.

The programs affect police, fire-fighters, municipal judges and both teachers and administrators in the school system. Other D.C. workers are covered by the U.S. civil service retirement program, to which both the city and its employes make regular payments.

The conferees reached swift agreement on the amount of the federal subsidy - $65 million a year for 25 years or a total of $1.6 billion.

This is less than the $80 million annual payment, or about $2 billion, that the Senate had approved earlier, but far more than the $47 million annually, or $769 million, approved by the House.

"That's good news," D.C. budget director Comer S. Coppie said when he learned of the decision.

Both chambers also approved a set of other changes, including a formula under which future pension payment increases would be tied to rises in the consumer price index rather than to future wage increases granted active workers. A costly 1 percent "kicker" designed to compensate retirees for a time lag it annuity increases would be eliminated.

As expected, the sticking point in the conference commottee was over whether tightened rules on the retirement of police and firefighters would apply to those already on the payroll, as the Senate voted, or only to those to be hired in the future, as the House voted.

One of the tightened rules would grant pensions after 25 years of service instead of 20. Others would curtail the controversial provisions that encourage a high proportion of police and firefighters to retire on tax-free disability pensions.

Rep. Tonald V. Dellums (d-Calif.), chief sponsor of the House bill, said fairness dictates that the rules should apply only to future personnel.

But Sen. Thomas F. Eagleton (D-Mo.) insisted on applying the new rules to everyone, saying the "excessive generosity andnabusive nature of the present system" threatens to bankrupt the D.C. government if allowed to continue unchecked.

Sen. Charles McC. Mathias jr. (R-Md.), a Senate conferee, said he agreed with the House position.

Eagleton, chairman of the Senate Governmental Affairs subcommittee on D.C. affaris, said Senate Majority Leader Robert C. Byrd and other influential senators are insisting upon the restrictive version.

When the deadlock became apparent, Rep. Charles C. Diggs Jr. (D-Mich.), chairman of the House D.C. Committee, suggested the conferees adjourn until Wednesday so Eagleton could discuss the matter anew with Senate leaders. Both said the bill must be passed this year, or it may never have another chance in future economy-minded sessions.

The disability provisions provoked a public and congressional controversy earlier this year when three high-ranking officers - former fire chief Burton W. Johnson, former police chief Maurice J. Cullinane and former assistant police chief Tilmon B. O'Bryant - retired in quick succession on full disability after long, active careers.