Betsy King, just out of LPGA qualifying school, gave a gallery that included her mother and father a thrill on the eve of her 22d birthday with a five-under-par 67 today, and took a one-stroke lead over Mary Mills after two rounds of the $100,000 Long Island Charity Classic.

The recent graduate of Furman University, named the school's woman scholar-athlete of the year, had a two-round total of 138, six under par. First-round leader Mills shot 68.71 - 139.

King, who finished second among 45 golfers at qualifying school two weeks ago, has more than Mills to be concerned about in the 72-hole tourney. All-time money leader kathy Whitworth, who has earned $721,957 more in official prize money than King, since she turned pro when king was 4 years old, fired a 68 to put her with jane Blalock, Sandra Post and Jo Ann Washam at four-under-par 140.

King had five birdies, no bogeys and never triple-putted. She missed only one green, the same 10th she birdied Thursday, when she hooked a shot into a sand trap. But a 20-foot putt rolled in to save par.

Meanwhile, a representative of Ram golf clubs, worried by the controversy surrounding the legality of irons made by the company, arrived and discovered that several players were using illegal irons.

Pat Bradley, Washam and Mills were among those whose clubs are made with grooves that are wider than regulation permit.

The problem arose at the men's PGA Championship Wednesday when the clubs of a number of players, including leading money winner Tom Watson, were checked and deemed illegal.

The LPGA had decided to hold off its inspection until this tournament was completed Sunday and allow players to continue to use Ram equipment. There are about 20 women currently using Ram clubs.

But Rams, apparently upset by adverse publicity, decided to make its own check, although it will not have a bearing on this tournament. The company representative discovered that the older clubs, used by this year's leading money winner, Judy Rankin, Post, Marlene Hagge and others, all seemed to be legal, while the clubs manufactured recently are illegal.

In Elk Grove Village, Ill., Allen Hansberger, president of the Ram Golf Corporation, said the problem stemmed from the custom grinding of some clubs made for touring professionals.

The specifications for grinding the clubs called for grooves in the club-face of 35-1000ths of an inch in width, the size allowed by U.S. Golf Association rules.

However, Hansberger explained, "In tracing the inaccuracy on these particular clubs it was found that while the specifications conformed to USGA rules, the clubface was inadvertently ground a fraction less than the specifications." Only touring pros' clubs were affected, he said.