S &K Famous Brands of Richmond, a menswear retailer, said this week that profits fell 37.3 percent in its second quarter compared with the same period last year.

Quarterly earnings were $160,400 (8 cents a share) on sales of $7 million for the period ending July 27, compared with profits of $255,800 (13 cents) on sales of $5.9 million.

For the six months ended July 27, S&K Famous Brands earned $195,800 (10 cents) on sales of $13.8 million, compared with $529,200 (26 cents) on sales of $11.6 million.

S&K Chairman Stuart C. Siegel said earnings continued to suffer from sluggish consumer spending, and noted that the firm had installed cost controls and tightened buying procedures.

"We expect sales comparisons in the second half to improve over that of the first half," he said.

The firm operates 31 S&K menswear stores in seven states and 11 Hip Pocket stores in Virginia.

*Merry-Go-Round Enterprises of Towson, Md., a retail clothing chain, reported a 39 percent drop in profits for the second quarter compared with the like period a year earlier.

Merry-Go-Round earned $945,000 (15 cents a share) on sales of $34.6 million, compared with profits of $1.5 million (25 cents) on sales of $33.4 million a year earlier.

For the six months ended Aug. 3, Merry-Go-Round earned $2.3 million (37 cents) on sales of $68.2 million, compared with profits of $4.1 million (66 cents) on sales of $69.9 million.

Michael D. Sullivan, the company's president, said profits were affected by a slowdown in consumer spending.

He noted, however, that this year's profit figures were being compared to "exceptionally high levels of sales and earnings" reported in the first half of last year.

Merry-Go-Round, which has been expanding rapidly, opened 19 stores in the first six months of the current fiscal year and now operates 290 stores.

*American Fuel Technologies of Federalsburg, Md., which produces and markets anhydrous ethanol, an octane enhancer for gasoline, reported a $4.4 million loss (34 cent a share) for the fiscal year ended May 31.

The loss was somewhat less severe than the company's $4.9 million loss in fiscal 1984.

AFT was hit hard when the cost of corn, used to make ethanol, rose sharply and led to curtailed production at the Maryland and Oklahoma plants. Temporary shutdowns at those plants cut sales for the year drastically.

The fiscal 1985 loss came on sales of $6.9 million. In 1984, AFT had sales of $9 million.

*Insituform East Inc. of Landover, Md., which repairs sewers and pipelines, reported more than a 300 percent increase in net earnings for the quarter ended June 30 compared with the same period last year.

Insituform had consolidated sales of $2.4 million during the quarter, compared with sales of $1.6 million for the like period in 1984. Net earnings were $253,353 (8 cents a share), compared with $59,000 (2 cents).

For the year ended June 30, earnings were 44 cents per share compared with 21 cents for the previous year.