The word "rare" stands alone. No modifiers such as "very", "almost", or "pretty" are properly used with the word. Among a handful of truly old model airplane engines that can properly be labelled "rare" is the 1949 Japanese MAMIYA 60 spark ignition. Gosh, you say to yourself, MAMIYA is the name of a camera... the Mamiya 645 of 20 years ago. From the late 1940s to the late 1950s Mamiya model engines were manufactured by one Minoru Sato, one time assistant camera designer at the factory in Tokyo. Owner Seichi Mamiya, a model enthusiast himself allowed Sato to use his name for the production engines.
This beautiful engine was a plain bearing shaft rotary-valve unit. Appearing at the time when the quality of Japanese engines was not up to the quality of the best American engines, it still looked quite modern and expertly done. It had for example, a cast-aluminum domed piston with two rings, an inclined spark-plug and generously ported cylinder liner fitted into a one piece casting with separate bolted on front and rear plates. A small backplate mounted gas tank indicated it was for free flight. The conrod was of diecast aluminum with unbushed ends. The hardened crankshaft had a large crankpin with a semicircular brass counterweight riveted onto the disc opposite the crankpin. It ran in bronze bearings in a diecast front housing. The bearing protruded from the front end and on it was mounted the ignition timer. It was of a neat design employing an adjustable diecast clamp with an open points assembly. The cam that formed part of the prop driver keyed on to a square on the crankshaft (a la Brown Jr.) ahead of which the shaft was threaded for a 7mm nut. An unusual feature of the front housing was its brass carburetor intake utilizing a spraybar equipped with a copper fuel pipe soldered on, and curving down under the crankcase to the gas tank. The Mamiya 60 had a strong resemblance to American designs and one can see a sort of "McCoyish" lower case and ends, a "Super Cyke" type intake, and other small bits and pieces of resemblance.
In 1957, production Mamiya engines were listing an .09 and a .15 and other records show couple of Mamiya 29s, one with ball bearings and a rear disc valve and rear rotary-valve, ball bearing glow 60. Mamiya motors seem to have faded from the scene in the late 1950s.
During this post WWII period in Japan, the genius of Segii Ogawa (OS) who had actually built his first model spark ignition engine in late 1936, thus rivalling Bill Brown had produced no less than a dozen types of engines by the time the Mamiya 60 appeared in 1949. Also along with Ogawa, the Enya brothers, Saburo and Yoshiro were completing their early sparkers and Fuji had come on the scene. All of these engines, collectors properly classify as rare indeed. Interestingly enough, a number of early Japanese spark ignition engines have been located in the USA as returning GI Joes brought them back after the war. Sadly of the engines found, OS especially, have vital parts missing such as timers, spark plugs, pistons which are not replaceable.
There is no lack of interest in obtaining these early "gems". The main reason, of course, that model engine collectors have been unable to build a collection around the early Japanese sparkers is their scarcity, even in Japan.
Thus if a collector was able to obtain one of the 1949 Mamiya 60 engines in new and complete condition it would be a remarkable event for him and for all collectors, too! Production numbers and current values are too elusive to pin down but.... be assured that the bidding would be very high dollar wise for these rarities.
See Also: David Owen's Mamiya 60 Restoration