Restoring a 1903 5 HP Samson Gas Engine


| July/August 2004



5 HP Samson engine

Lester Bowman's 1903 5 HP Samson Model N.

Photo by Lester Bowman

1903 5 HP Samson Model N
Manufacturer:
Samson Iron Works, Stockton, Calif.
Model: Model N
Year: Circa 1903
HP: 5
RPM: 300
Serial number: unknown
Bore: 5-1/2-inch
Stroke: 10-inch
Flywheel diameter: 36 inches
Governor: Flyball, volume governed
Ignition: Low-tension
Cooling: Tank

Samson engines have always intrigued me, and I've always wanted an early Model N. Fortunately, a good friend helped me to acquire a circa-1903 5 HP 'web spoke,' so named by Samson collectors for the inboard counterweight cast into one of the 36-inch flywheels. Designed by John M. Kroyer, this Samson is a long-stroke (5-1/2-by-10-inch bore and stroke with a 2-inch-diameter crankshaft), slow-speed, volume-governed gas engine equipped with Samson's later-style one-piece igniter.

The past owner started restoration but, unfortunately, died before he could finish it. When I bought the Samson in 1998, it was set up on a cart with a cooling tank. Another good friend hauled it to my home in Modesto, Calif., and before I worked on it all 1 could do was sit and admire it for several days.

Samson engines are beautifully proportioned with large flywheels and turned connecting rods that are fitted with heavy brasses. Both valves - as well as the igniter - are mounted in the pre-combustion chamber. The governor is belt-driven using a balanced valve while a peculiar valve link controls the four-cycle events. All Samsons are tank-cooled, throttled-governed engines using poured babbitt for the mains and low-tension ignition.

If it's not one thing, it's another
Once the initial thrill of acquiring the Samson had passed, I began checking it over. For starters, the timing was so far advanced it wanted to take the skin off my hands even on retard. I reset the ignition and tried again, but it would only run for a little while and then die. But if I waited a few minutes, it would start right up again. While dealing with this problem, I learned a very important lesson. Studying the points under a magnifying glass, I noticed they were 'brassy' looking. Further inspection revealed someone had built the points up with brass brazing rod. I made new points to correct the problem and reassembled the Samson. I now had excellent spark, but the engine turned over too stiff. Checking into it, I found the main bearings were tight so I shimmed them as needed.

Now I had the Samson running, but the governor spindle shaft kept binding in the valve body. It turned out the shaft was bent and I ended up making a new one because I couldn't straighten the original to my satisfaction. Now the Samson governed properly, but the igniter trip rod kept sticking, causing the engine to die. I repaired that problem as well as the flooding mixer, which had a rotted-off fuel needle valve. Finally, the engine ran very well, never missing a lick.