A growing number of top mortgage-market economists now believe that we've seen the peak for home-loan rates for the year, and are in for a slow, bumpy drift downward for the rest of the year. However, few of those experts believe fixed mortgage rates will go below 13 percent during the coming six months.

None of these experts holds much stock, either, in presidential-election-year theories of mortgage rates. They say that without a significant cut in the billowing federal deficit, the odds favor high money costs for home buyers and sellers to continue throughout 1984, no matter who's running.

So, if you're trying to time a home sale or purchase, don't assume that because Ronald Reagan is likely to be looking for votes next spring and summer, mortgage rates somehow will be hovering magically just above 10 percent. It's not in the cards.

Economists say that mortgage rates are traveling on a course produced by two powerful, conflicting sets of forces.

On the positive side, the Federal Reserve Board's tightening of the monetary screws has achieved much of what the Fed sought.

The economy--especially housing--has cooled from its booming pace of early spring. Monetary growth is heading back towards the healthy zone again. Inflation is still in the low single digits, and new borrowing demands by private industry are tailing off. By all traditional measures, interest rates should begin to moderate, and perhaps already have.

On the other hand, we have a looming, dark force in the capital markets: The federal deficit shows no sign of coming under anyone's control in the foreseeable future. The government has to plunge into the money market for $110 billion in the last half of 1983 alone--including an estimated $65 billion from October through December--just to feed itself. The sheer dimensions of the federal presence in the market amounts to a "constant, upward pull on interest rates," according to Peter Treadway, economist for the Wall Street firm Cralin Associates.

"As long as the deficit numbers stay in the range they are, it's not realistic to expect rapid mortgage-rate declines," Treadway added.

Nonetheless, Treadway is an optimist. He believes that the positive economic forces underway will be sufficient to ease rates down to 13 percent--or even 12 1/2 percent--by early 1984. Slower growth in the economy overall during the coming half-year will produce lower money costs across the board, even with the deficit stuck at the $200 billion level, according to Treadway.

The chief economist of the Federal National Mortgage Association, Tim Howard, similarly forecasts lower rates, but he'd be happy with 13 to 13 1/4 percent for conventional mortgages by January. Mark Reidy, executive vice president of the Mortgage Bankers Association of America, is in the same ballpark.

What does this emerging, mildly optimistic consensus among mortgage-market specialists mean for you as a buyer or seller in the coming six months? How do slightly lower--but barely tolerable--mortgage rates fit into your strategy?

Here are a few suggestions:

* If you're a potential buyer, don't bite on the 14 percent fixed-rate-mortgage hook many lenders are dangling. Consider instead a deeply discounted adjustable-rate loan in the 11 to 12 percent range--preferably one with no prepayment penalties and built-in protections against sharp payment rises in the future. If the economists' forecasts are right, now is an ideal time to go the adjustable-loan route because there's relatively little "upside risk." You start out with a low rate, and if you pick a short-term rate adjustment index, you're likely to get an even lower one.

* If you're an individual seller or a home builder, give some thought to one- to three-year "buydowns" (rate subsidies) to 11 1/2 or 12 percent to pull in purchasers. Lending institutions can readily arrange these transactions for individual sellers. As a buyer, a rate of 2 to 3 percent below the current market may be irresistible.

* Cheer up. Housing demand is still strong, according to all consumer polls, such as the latest from the University of Michigan Survey Research Center. All that's needed to turn demand into sales is moderately cheaper money. Rates aren't going back to the bad old days of 1981-'82. They're drifting downward, and sellers and buyers have plenty of mortgage tools available--conventional and creative--to swing the deals they want.