Washington utility executives said yesterday they are converting from oil-to coal-burning power plants at an even faster pace than President Carter has called for and they predicted the president's energy plan will speed up the shift from oil to natural gas for residential heating.

It is the economic advantage of burning coal and natural gas, rather than presidential pleas, that is changing the sources of fuel, said officials of the three local power companies.

Potomac Electric Power Co. generates an average of 80 percent of its electricity from coal and this summer is burning almost 90 percent coal, said Donald R. Briggs, vice president for production.

Briggs said Pepco plans to close its oil-burning plant at Buzzard Point in the District of Columbia and is on the verge of eliminating oil-fueled plants except for those needed to produce power at peak demand periods.

Virginia Electric and Power Co., which now gets 39 percent of its electricity from oil-burning plants, plans to reduce that to 16 percent in the next 10 days, said President Stanley Ragone.

But, Ragone added, "the president has not yet provided the means" for cutting the use of oil to generate electricity. He cited the environmental restrictions on coal burning and uncertainties about nuclear power. The nuclear question is critical for Vepco, because the Richmond-based company plans to replace its oil plants with nuclear facilities.

While the utility executives are contemplating the shift way from oil, landlords and homeowners are inundating Washington Gas Light Co. with requests to replace their oil burners with natural gas.

"We've been literally flooded with requests," said WGL spokesman Paul Young. He said 150 commercial building owners have asked to switch to gas and hundreds of residential customers have been calling every day about converting.

Young said the current price of natural gas is equivalent to heating oil at 45 cents a gallon; oil prices are predicted to reach $1 a gallon by the end of the year.

Utility executives said they don't yet know the impact of Carter's plans to make them finance insulation, storm windows and other energy-saving investments for their customers.

Investors immediately reacted to the president's energy messages by scrambling yesterday for the stocks of two Washington firms that expected to benefit from changing energy policies.

Dynalectron Corp., the McLean firm that is a leader in developing processes to convert coal into petroleum, was the most active stock on the American Exchange, and Auto-Train Corp. was Amex's biggest percentage gainer.

After 296,000 shares changed hands, Dynalectron closed at 15 3/4, up $1.50 a share.

The stock of Auto-Train - which says its reservations have soared since the gas lines formed - climbed 19 percent in value yesterday, increasing 75 cents a share to $4.625.

There was good news in the president's speeches for two other Washington area businesses which plan to build oil refineries - Steuart Petroleum Co. and Hampton Rhodes Energy Co.

Steuart chief Leonard P. Steuart II and John Evans, president of Hampton Rhodes, said environmental road-blocks should be eliminated by the Energy Mobilization Board that Carter promised will cut red tape tying up energy projects. CAPTION: Picture, Potomac Electric Power Co's coal-burning generating station on the Potomac River in Alexandria: cost cited.By Ken Fell - The Washington Post