An experimental government program to link pay raises for rank-and-file white collar workers outside union jurisdiction directly to job performance seems sure of starting, despite last-minute congressional objections.

The test planned by the Navy could serve as the model for a system that would eventually scrap the system of automatic October pay raises for thousands of government workers, from clerks to scientists.

Under the test, first of its kind in the bureaucracy, Navy will put thousands of civilian laboratory workers in San Diego and China Lake, Calif., under a so-called "modified merit pay system.

Modified merit pay puts workers not covered by union contracts under an entirely new pay-reward system.

Instead of automatically getting the full amount of each October raise, workers would have to earn marks from bosses. Those who got poor ratings could get less than the regular raise given under white collar aides.

The experiment being considered by other agencies (including Health and Human Services) is a radical departure from the present pay system.

An appeal to delay the Navy startup until mid-September was made by Rep. Gladys N. Spellman (D-Md.), to the Office of Personnel Management.

Under the civil service reform act, OPM has authority -- subject to congressional review -- to okay modified merit pay experiments.

Bear in mind that regular merit pay for supervisors and managers is not at issue here. Thousands of Grade 13 through 15 workers, designated as supervisors or "management officials" already have been slated for a permanent shift to an even tougher form of merit pay.

Under the supervisor-manager system, they would be guaranteed only half the regular October adjustment. To get more, they would have to get higher marks from bosses.

The modified merit pay experiments -- limited by law to no more than 50,000 of the government's million white collar aides -- assumes they will get the full October raise, provided they get satisfactory ratings.

Funds to finance higher raises possible under both forms of merit pay would come from savings made by eliminating automatic within-grade longevity pay steps for all employes involved.

OPM cleared the Navy experiment in mid-April. The test was due to begin yesterday. Under the law authorizing the modified merit pay experiment, Congress has 60 days to veto experiments once OPM has okayed them. The 60 days was up yesterday.

Spellman who chairs the compensation subcommittee of the House Post Office-Civil Service Committee said the last-minute appeal to delay the Navy test was made because her subcommittee had not been fully briefed on it and last-minute questions had been raised by staffers and Navy personnel.

In hand-delivered letters to the head of OPM and Secretary of the Navy, Spellman said the experiment -- which would make substantive changes in the way government workers are graded, classified, rated and paid -- should not be made until Congress has more time to study Carter's proposed federal pay reform plan.

Based on his proposed pay reforms, Carter said federal workers this October would be due a raise of about 6.2 percent, although data under the current "comparability pay" law indicates raises nearly double that amount are justified.

An OPM official said that his office and the Navy were "deeply concerned" about the Spellman appeal, but felt that the groundwork for the project was "too far along" to delay it at the last minute.

Whatever the outcome of the modified merit pay experiments, they are sure to have one immediate effect: a shot-in-the-arm for union recruiters. The pay-performance would not cover workers in agencies or departments with "exclusive" bargaining contracts with unions. That should prompt a lot of people nervous over how modified merit pay would work, to look for the union label.