The Yin Yan diesels were manufactured in Shanghai, China, initially at a facility known as the Teh Ming Sport Goods Factory. They first appeared in 1962. Interestingly enough, their basic design was modelled quite closely upon that of the Alag range which had been manufactured in Hungary between 1955 and 1959. In around 1966 their name was Anglicised to Silver Swallow, but the basic design of the engines was little changed.
The engines appeared in both 1.49 cc and 2.47 cc displacements. The early Yin Yan models were very well-made indeed, meeting or even exceeding accepted contemporary standards for sports diesels in Britain and elsewhere. After the name change to Silver Swallow, ongoing manufacture seems to have shifted about somewhat among different companies, leading to a noticeable variation in quality as well as a variety of names. However, the majority of the engines ran just fine, although some examples could benefit from a little "fettling" by their owners prior to being run. Once runnng, they performed at a more than acceptable level by contemporary sports diesel standards.
The situation was retrieved in around 1994, when the CS company, also of Shanghai, acquired the designs and tooling. They continued to intermittently produce their own versions of the engines at a generally good standard into the first decade of the twenty-first century. The examples manufactured by CS are generally far better engines than many modellers would give them credit for.
An article about the Yin Yan/Silver Swallow engines remains available on the late Ron Chernich's superb "Model Engine News" (MEN) web-site. However, a great deal of additional information has since come to light, and a revised and updated article providing a wealth of further detail may be found on this web-site.