President Carter's civil service reform act has proved a bonanza for contractors and consultants who specialize in telling federal agencies -- for a price -- how to rate and grade their employes, set up merit pay systems and find more blacks and Hispanics.

Under the law, Uncle Sam is supposed to give special attention to recruiting minorities for jobs, grades and geographic regions where they are "under represented" in relation to their numbers in the general population, or in colleges. The law also requires federal agencies to set up merit pay programs -- to replace automatic pay raise procedures -- and contractors have already been paid millions to tell agencies how to spot, identify and reward good people.

While buying outside expertise (with taxpayer funds, government agencies are also turning more to minority-run consulting firms that specializde in locating blacks, Hispanics and other minorities for federal jobs.

(This program has provoked bittersweet reaction among minorities -- and especially women -- already in government. Many of them feel they have worked hard, paid their dues and learned procedures but are being overlooked while agencies and their consultants seek to bring in new minority blood, to make their numbers look better).

The drive to get more women and monority group members into government has resulted in some novel techniques by different agencies:

The State Department has lowered the passing score for blacks who take its tough Foreign Service Officer exam. Under new rules, black candidates need a score of only 70 to pass and be considered. White candidates must score at least 75.

The Labor Department has hired outside consultants to help it recruit 300 Hispanic farm workers for low-paying clerical jobs in more than a dozen agencies here. The primary firm hired to find the Grade 2, 3 and 4 job applicants, prepare them for tests and bring them here and house them has subcontracted with two other groups to accomplish the task. Similar programs are planned by Labor and other agencies, despite the fact that unemployment among black teen-agers here is at the 40 percent level.