Nelson Plugs - If you get a Nelson head for one of your engines you will obviously need some Nelson plugs. The are two sources that I use. Doug Galbreath at http://www.the-printer.net/DookCat.html has Nelson heavy duty plugs and other items for Free Flight. Kitting It Together at http://kittingittogether.com/ also has the Nelson heavy duty plugs as well as the “Hot” or standard Nelson plugs and the flat coil Nelson plugs. Personally I only use the heavy-duty vertical plugs and the standard duty flat coil plugs. Older versions of the vertical coil heavy-duty plugs have a little notch as shown in corner of the hex of the plug as compared to no notch for the standard Nelson plug. New stock has a glass/epoxy seal and no notches. For the Cox 049 engines and the Holland Hornet Nelson heads can be economically obtained from Doug Galbreath. For most other engines I will gladly custom make a Nelson head to fit. Note that I carry a partial line of Merlin plugs which can also be used with the Nelson recess. Please see the Commercial Parts page for pricing and styles available.
Plug Torque - Don’t go crazy with the torque you apply to the Nelson plug. 36 in-lb is plenty and do not torque while the engine is hot unless the lift is blowing through. It is a good idea to get a torque screwdriver and use it for torquing head screws as well as the plugs. You usually can get a Utica TS-35 Torque screwdriver on ebay for about $50 or less. Retail is almost $300.00.
Fuel – Please use at least 25% oil in your NOS fuel with ½ of the oil or more being castor. This is very important for those old sleeve main bearings and iron pistons. I use about 15% nitro in all my NOS engines except for the few times I fly ½ or ¼ A events. With structurally strong engines you can easily push the nitro and many do up to 50% but I still do not recommend that practice. K&B Green Heads, early Vecos, most NOS legal Foxes, and early Johnsons are not structurally strong. OS MAX IIIs, later Vecos, the Johnson CS and the Fox 35 Black Head Combat special and 29X all seem structurally strong.
Bladders – A really neat bladder is something called “The Little Red Cap”. It looks like a condom for a Gerbil and provides a pressure level that is lower than that of a pacifier but higher than for a penny balloon. The lower pressure level makes many of the original needle valve assemblies work just fine and needle adjustment is very easy. It can be cut off slightly longer than any of the various smaller diameter sections and used for engines from 0.020 to all but the largest engines. If you mount it externally, where the sun can do it’s thing, you should protect it with a penny balloon. The Little Red Cap web site is http://www.littleredcap.com/ along with a list of retailers. Cost is extremely reasonable from Rockler Woodworking and through Amazon.com. Rockler’s web site is http://www.rockler.com/product.cfm?page=5685&filter=little%20red%20cap . I have been using the this bladder on my test stand for all but 0 size engines and they last for months. It was discovered by Dick Covalt and we have been using it for three years with excellent results. We don’t win more contests but our engines are happy and easier to needle. I stock a limited supply of the “Little Red Caps” as described on the Commercial Parts page.
