Ralph,

In the 1/2A world, as in a Cox engine, the entire head is the glow plug. Why did they do this? If you take one of these heads and bore it out and tap for a standard glow plug, and you maintain the correct compression ratio, you lose up to 1.5K RPM, (out of 18K).

Turbo plugs have a tapered seat at the bottom of the plug, isolating the threads from the combustion chamber. If you install a turbo into a Cox head, you get back your 1500 RPM and in some cases get a little more. This allows you to play with the multiple heat ranges available. Larger engines don't use turbos because this effect is less pronounced. In this case, with a gasser, that'll likely be true as well but for a couple of hours work, no more than making a head with stock plugs, it's worth a try. Just to see.

AV8TOR,

Yes, I'm familiar with the concept. However, to work it depends on using a very expensive, all ether fuel along with the oil. The heated copper slug was to allow more leeway with compression ratio. A neat idea that's workable but that ether,,,,

A stock, diesel fuel contains typically, 50% kerosene, 30% ether and 20% oil. There are many variations on this, notably lots more oil, up to 30% for traditional, cast iron diesels. Imagine running such a fuel in a 23cc diesel. Which isn't necessary, all that oil is typically because of the bushed rods in stock model engines. We have bearings all around and this allows us to get away with down to 1% oil in some cases.

My diesel dabblings led me to try running these engines with no ether at all. Considered impossible, I managed to do just that as long as you use a high ether prime mix along with using an electric starter. This last is considered a WMD by the general diesel community for good reason but with care, it can be done. Illustrated here.

http://www.youtube.com/watch?v=OOS9eVC0fjo

From there, the idea is to run a diesel gasser conversion with just kerosene and very little oil, down to a minimum of perhaps 5%. That would depend on the oil and that's where the experimental fun really begins. The really crazy notion is to run a pure kerosene fuel. Kerosene in another form is called home heating OIL. That means the fuel itself has SOME lubricating properties. How much? Will it be adequate? I hope to find out. [:@]