Historical information

The Underwood Motor Manufacturing Co started making 3hp 2-stroke engines, in either marine or stationary styles from about 1946 at 135 Queensberry St, North Melbourne.
By about 1949 the 3.5hp 4-stroke engine was introduced. this engine was sold by Baltic Simplex as the Simplex Challenger, replacing the RB&T built S type.
By the mid 1950's the firm had shut up shop. In the Sands & McDougall directories of 1948 & 1949 they were listed as Underwood Petrol Engine Co. The following years they were back to Underwood Manufacturing Co.
The two-stroke version came in such variations as marine, stationary, tank, hopper cooled and air cooled, each believed to have run on a mixture of 30 parts Standard grade petrol to one part oil.
Most but not all water cooled two stroke engines feature a water circulating pump.
The 3-4hp four stroke engine used petrol for starting then switched to kerosene when warmed up. Most were 3hp.
From a 1947 advertisement the machine was noted with rope start, quickly detachable magneto and the angled spark plug which would have been a marine version with a clutch and hand throttle. The stationary engine had the clutch replaced by a governor. The magneto on these engines did not rotate. it was oscillated by an eccentric on the crank and a link to an arm on the magneto drive shaft.

There were other variations including a hopper cooled one with a normal marine base and a chain driven magnet.

Physical description

Dark green with surface rust "Underwood" in white lettering on red background on tank.