RE: cox engine
The Tarno carb was great wit exactly the right fuel, prop, and weather conditions. Getting everything right was on the point of being impossible.
The early Cox r/c 049 and 051 engines were supplied ex-factory with a carb that looked exactly like the Tarno, and may well have been the real thing. See the first picture, and the center engine in the second.
A major redesign was done, adding not only an adjustable air bleed, but a genuine muffler. The later engines (I have three) work very well. If you can find a [u[TeeDee 05 R/C[/u] it will serve you well. But they weren't cheap. The cheapest one I've gotten was $82.95 plus tax.
As an alternate, go to the 1/2 and 1/8A forum, an active user there who goes by "Dickeybird" has done some engineering on Cox throttles, his way is much less expensive. Check it out.
Bill.