ORIGINAL: aspeed
Don't forget the Tee Dee .049 carb is 1/4" 32 UNEF (unified national Extra fine I think). I am making all of my heads with the Turbo plugs now. 8mm x .75 .May as well get an extra 1000 rpm if you are going to the trouble of making a head. The Nelson plugs are harder to find the tap and are a bigger diameter for the smaller motors. And to get off the topic, I wouldn't mind reading a MA mag again for a change. I thought they were fairly good for the few I read.. They only print what is handed to them in most cases likely. If no one contributes then they get kind of dry. (zone meetings and rule changes) I read MA Canada and it is kind of similar. We can contribute articles if we want, and they might get printed depending on things.
That isn't a bad idea using turbo plugs. The small 1/2a engines are quite sensitive to the slight compression loss from just the threads on a glow plug. So using a turbo plug that seals at the bottom does correct for that issue.