Dough Greer hasn't forgotten the day in 1918 when his grandfather rolled a 40-horse-power J.I. Case live steam traction engine onto his farm in Paris, Ky.

At the time, he was 6 years old and not yet ready to mount the huge machine and squire it around the wheat, oat and clover fields. But he watched his father and grandfather operate the engine until, when he turned 16, he took hold of the throttle and, in his words, "became a man."

This week 49 years later, Greer is exhibiting a Keck-Gonnerman engine much like the one he first drove on his family's farm as part of the "America's Appetite for Energy" exhibit in the Smithsonian Institution's Festival of American Folklife.

He and fellow exhibitors will use the machine to thresh about 300 bushels of wheat that later will be milled and baked into loaves of bread. The demonstrations will be held at noon and 3 p.m. today, Saturday, Sunday and Monday. No demonstration are scheduled for Friday.

Greer, 65, ran his grandfather's steam engine until he entered Knoxville College in Tennessee in his late teens, and by that time "the oil and steams was in my blood," he recalls.

So in 1972 when he retired as a chaplain and historian for the U.S. Army Reserves in Washington. Greer returned to his native Kentucky and bought the Keck-Gonnerman engine.

Since then, he has spent many hours and about $6,000 refurbishing the 80-horse-power, coal-burning engine, which weighs about 10 tons.

The fruit of his labor is a shiny green-and-red tribute to an age when engines like it with names like Case, Geiser and Frick lumbered across the nation's farmlands.

To some, the machines may seem noisy, hot and bulky, but their devotees will tell you that they inspire respect.

Greer said he meets "a lot of the cream of America" when he exhibits his machine.

"Anywhere you find a bunch of steam buffs together, you find a mighty good cross-section of America," he said.

Greer, who has been a teacher, a special assistant to an administrator of the Farmers Home Administration (FHA) in the 1940s and pastor of the 13th Street Chruch of Christ since 1947, credit some of his success and motivation to operating his grandfather's steam machine back on the farm in Kentucky.

"Operating a big machine like that teachers you respect for power, because you learn that power misapplied can be catastrophic," he said.

He said he only had two run-ins with misapplied power - once when the engine fill into a stream (no one was injured) as a result of a weak bridge. Another time when he blew grain into his grandfather's face, not knowing he was standing in the line of fire behind the thresher attached to the machine.

Being closely involved with older men and machines provided him with heroes to revere, Greer said, something he thinks today's youth, especially boys, don't have.

"The older men I worked around were my heroes," Gleer said, adding that running the machines was privilege.

"When you got up on the machine for the first time knowing that you were in full command you felt you'd reached the zenith of being trusted," he said. "You suddenly became a man."

"You were at last walking in the footsteps of the heroes you had been watching over the years."

Young boys today don't have the same opportunities to develop a healthy love and respect for older males by working closely with them, Greer commented.

The young male is becoming highl frustrated because he is deprived of heroes and lacks identity because he doesn't have chances to prove himself and feel important, he said.

As a pastor, Greer said he counsels many young couples with marital problems stemming from the male's lack of confidence and identity.

When he's not busy with his 200-member congregation. Greer, who lives in the District slips away to his machines at the Carroll dounty Farm Museum in western Maryland to po lish it up a bit with kerosene and maybe adjust a valve or two.

"Once you get this oil steam into your blood, it's hard to get it out," he said.