A blue-ribbon panel studying the Carter pay reform plan (which would "reform" this October's federal salary hike from 10.9 percent down to 6.2 percent) says reform may be a terrific idea, but . . .

The task force of the American Society for Public Administration thinks Congress needs more data before the new systems proposed by "reform" are adopted to compute future raises for federal civil servants. Each 1 percent pay hike costs about $500 million.

Specifically, the ASPA task force feels the Administration may have unintentionally used some misleading advertising, saying reform would save the taxpayers $2.8 billion. And it worried about the government's ability to switch from straight salary match ups with industry to the complicated "total compensation" system. It would weigh, measure and assign values to pay, sick leave, vacation, holidays and retirement and use them to set federal pay raises.

Although ASPA isn't Tip O'Neill or Robert Byrd, the Administration craves its acceptance of pay reform. ASPA is a national outfit with clout and contacts of its own in Congress, state houses and corporations. It will consider the task force report this April at its national conference here. If ASPA buys the recommendations, that could persuade some members of Congress, governors and business types to take a harder look at reform.

The task force, chaired by Linda L. Smith (assistant to the director of the Office of Management and Budget) generally supports reform. It thinks the president's plan is on the right track. However, it does want some issues considered, including the following: t

The matter of giving the president greater leeway to readjust federal pay rates draws its opposition. The task force feeling is that pay raises arrived at under the president's "reform" machinery should be virtually automatic, not subject to political reviews and cutbacks.

That it believes the Administration has borrowed a leaf from former Defense Secretary Robert McNamara who made "cost avoidance" part of the nation's fiscal-political vocabulary. Critics of cost-avoidance note that an individual could save $25,000 by announcing his decision not to purchase a Mercedes sports car. Many see cost-avoidance as the art of taking credit for not doing something you probably wouldn't or couldn't do anyhow. The ASPA group is suspicious of the $2.8 billion "savings" billed as a benefit of pay reform.

The task force pointed out that presidents frequently shave the amount of pay raises due federal workers, and it is incorrect to assume future savings -- from reform -- by cutting raises that probably would not have been given in any case.

It also says the Administration should supply working models, data and details on how it would accomplish such reforms as linking federal pay scales to hometown private industry rates.

Task force members, some of them top budget and administrative people in government, investment and management firms, believe Congress should demand more details before it buys reform, although it likes its outline and general concepts.

The task force report, if it is adopted by ASPA, won't be enough to stop or derail the Carter Administration wants enacted into law this year. But it could be a pebble in the shoe that would slow, and irritate Administration aides as they march up the hill to pay reform.