The nation's two largest automakers-General Motors and Ford-reported record sales and profits today for their operations throughout the world. GM's profits leaped 49 percent during the first quarter over last year's figures.

GM's stranglehold on nearly half the U.S. auto market brought sales of $17.9 billion during the first three months of 1979, compared to $14.9 billion in sales a year ago. Profits rose steeply to $1.3 billion ($4.39 a share) compared to $870 million ($3.03) last year.

Ford's 28 percent increase in profits-$12.6 billion ($4.97) from $467 million ($3.93)-came from its surgling sales overseas. A massive 63 percent of Ford's profits came from operations abroad in the three-month period.

Overall sales for Ford were $12.6 billion in the quarter, compared to $9.9 billion a year ago.

Ford's profits from U.S. operations actually fell in the quarter by two cents a share.

Besides its huge quarterly increase in profits, GM reported its first year-to-year improvement in profit margin on sales since 1976-from 5.8 percent to 7.0 percent.

Despite their mutual record-setting, the two companies differed markedly in their assessments for the future of auto sales.

GM's top executives, Chairman Thomas Murphy and President Elliott Estes, maintained that 1979 will be a good year for business and that the economy has a "fundamental soundness . . buoyed by rising income."

The two stood by sales projections of several months ago that combined vehicle sales in the U.S. will hit or top 15.5 million in 1979.

In numbers, GM's sales of cars, trucks and buses in combined operations rose from 2,335,000 to 2,470,000 while Ford's rose from 1,625,000 to 1,803,000.

Part of the increase during the first quarter, GM said, was attributed to recovery from the cold weather and the coal strike in the first quarter a year ago.

In a joint statement, Ford Chairman Henry Ford II and President Philip Caldwell hailed the company's higher profit gains outside of North America.

Will M. Caldwell, Ford vice president for finance, said that British and German earnings accounted for most of the overseas profits, but Argentina and Brazil made important contributions. He said changes in currency rates contributed 9 cents a share to Ford's profits.

Ford, however, warned that its results for 1979 as a whole might not reflects the good first quarter because "U.S. gross national product and consumer income, which also increased in the first quarter, are likely to increase less rapidly later this year, thus unit sales may not continue at first quarter levels."

Henry Ford II just recently boosted his projection for U.S. car sales from an earlier 10.8 million to 11.1 million for 1979. The company's statement yesterday, however, mildly hedged that projection by saying it had included "no allowance for a strike." Its three-year contract with the United Auto Workers expires in September.

Ford plans to increase capital spending to $3.5 billion this year, up $1 billion from a year ago. Three fourths of that sum will be spent in North America for the development of new vehicles to meet mileage and emissions limits, Ford said. The company expects its capital outlays to remain at that level throughout 1982, a new and higher projection.

News services also reported the following earnings:

Mobil Oil Corp., the nation's second largest oil company, reported an 81 percent increase in first quarter profits benefiting, like other major oil firms, from sharp increases in world petroleum prices.

Mobil, like top-ranked Exxon, which reported its earnings earlier, also said the stronger dollar on currency exchange markets helped improve profits.

Mobil said its earnings rose $437 million in the first quarter ($4.12 a share) on revenue of $10.3 billion. In the 1978 first quarter earnings were $241 million ($2.28) on $8.7 billion in revenue.

Sun Oil Co., the 11th largest oil company, reported a 43 percent gain in first quarter earnings to $120.3 million ($2.24) on revenue of $2.36 billion. In the comparison 1978 quarter, Sun reported earnings of $84.3 million, or ($1.57) a share, on revenue of $1.7 billion.

Standard Oil of California, the fourth largest oil company in the nation, said its first quarter profits rose nearly 43 percent to $347 million while smaller Amerada Hess Corp. showed earnings more than tripled from the year-ago period to $115.6 million.

SoCal's $347 million in first quarter profits translates into earnings of $2.03 a share, up from $1.42 a share a year earlier. Its revenue was $6.92 billion in the latest quarter, up from $5.69 billion.

Amerada Hess had earnings of $115.6 million ($2.84) up 259 percent from $32.3 million (80 cents). Revenues rose 13 percent to $1.53 billion from $1.35 billion a year earlier. The company said neither this year's quarters were typical ones but cited higher prices of oil and gas as the major reasons for its sharp profit gain.

Kerr McGee said its profits were $33.4 million ($1.29), up from $17.7 million (68 cents). Revenue in the latest period was $601.9 million, up form $482.9 million.

At its annual meeting, Twentieth Century-Fox Film announced revenues increased slightly in the first quarter, from $158.9 million to $159.5 million. Net profits per share grew from $2.21 to $2.33.

Phelps Dodge Corp., the copper producer, doubled its profit in the first quarter to 61 cents a share from 29 cents a year earlier.

Net income rose to $14.1 million on sales of $314.4 million compared with $7.4 million on sales of $320.3 million.

The gains were made despite a $2.9 million loss by Phelps Dodge's uramium subsidiary, Western Nuclear. Increased copper production and better prices produced the gains.

Atlanta-based Delta Air Lines reported a 4 percent drop in first quarter profits, blaming it on discount fares, increasing csts and weather, which more than offset improved passenger traffic.

Net income amounted to $26,197,000 ($1.32) for the quarter ended March 31, compared to $27.4 million ($1.38) last year. The 1979 total included an after-tax gain of 16 cents per share from the sale of aircraft and an after-tax loss of two cents a share on foreign currency translation.

"The impact of deep discount fares, escalating costs and weather conditions combined to offset the excellent growth in passenger triffic," said Robert Oppenlander, senior vice president-finance.