It was a contest to see who got here first - the Americans with a new roof for their embassy or the Russians with a new winter. Despite an adverse call by an official, the Americans won. They rolled up a yellow-and-black crane with a stunning 178-foot boom, and as curious Muscovites watched, they put the race away, lifting load after load of building materials to the top of the fire-damaged embassy.

That made it all but 100 per cent sure that Navy Seabees can build a permanent new roof before the snow flies, which in the normal course of events here could be within a few weeks.

The officiating that could have hurt the U.S. cause occurred at the gate of the exhibition park where the American-built crane had been on display.

The gatekeeper said the crane couldn't leave because its papers weren't in order. "We drove out anyway," said one of its crew members.

The machine, manufactured by the Harnishchfeger Corp. of Milwaukee, Wis., took a few hours to do what had threatened to consume days. The Soviets had been unable to lift material onto the embassy roof, which was destroyed by fire Aug. 26-27. The Seabees faced the loss of precious time building their own lift.

Ambassador Malcolm Toon spotted the crane sitting in an exhibit of industrial equipment. John DeVane and Leo Welt who had brought it to Moscow from West Germany by flatbed truck several weeks ago in the hope of selling it to the Soviets, agreed to drive it to the embassy whenever it was needed.

The self-Propelled crane - identical to those used on the construction of Washington's Metro - is the size and weight of a tank. It can lift as much as 70 tons at a time, but with its boom extended, as the embassy job required, lifts about 3 tons per load.

Yesterday DeVance and Welt were that 30 tons of roofing materials would arrive from Finland today. With driver Herman Hartmann they got past the gatekeeper, made the 20-minute drive to the embassy, and with the help of some Seabees rigged the telescoping boom and raised it in front of the 10-story building.

"We were scared to death," Welt said. He had sold such machines, but had never rigged one. The Americans found help in the glove compartment of the cab - an owner's manual.

The crane got the materials to the roof without a hitch, and by mid-afternoon it was being unrigged. Hartmann drove it off to the exhibit to be on display until next week, when it will be needed again at the embassy.

"I hope our papers are in order," Welt fretted. "They really must let us back in."