Replacement screws for Cox engines
Sometimes it can be difficult to obtain genuine Cox replacement parts. The following table lists some of the screws used on Cox engines.
Note: please check with your engine before you buy: - I will not take any responsibility for errors in the list. If you have additions or corrections I will be happy to add them to this page.
The thread dimensions are the usual US designation of the form "drill# - threads per inch". This means a #2-56 corresponds to a #2 drill and has 56 threads per inch. All screws are of the NC/UNC type.
Gas transfer systems in Cox .049 engines
The cylinders of these Cox engines came with three different porting systems. These differ in the arrangement and number of transfer channels. Initially these transfer channels were milled with a single milling operation, resulting in a single, wide transfer flute; cylinders could have a single or a pair of two opposing flutes.
With the development of the Tee Dee and Medallion series it was discovered that the addition of one or two narrow secondary flutes would increase performance notably. Therefore these engines were equipped with either a single boost flute (the Medallion family) or two boost flutes at each edge of the basic transfer flute. Only some of the Bee family engines were equipped with such cylinders, most noticeable the Venom engine.
An additional feature built into the cylinder is the height of the lower edge of the exhaust window. This edge can be machined low enough for the piston skirt to open a slot below the piston when the piston is at top dead center. This is called sub-piston induction because the engine can suck in an additional amount of air directly into the crankcase, thus bypassing the carburetor. This works only well as long as no muffler is used. A muffler would lead to the induction of exhaust gas instead of fresh air.
Cylinders for Cox .15 engines
Last modification of this page: 21.05.18
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