Nelson turbo plugs...hot, or cold?

Thanks a lot Ken. This will help me identify the few Nelson heads I have.

Could we please stop conflating two different items-there are Nelson plugs-and there are turbo plugs...full stop! They're not the same thing, they are not interchangeable-the only things they have in common is a taper seal, and being physically larger than a standard 1/4-32 glowplug. Nelson plugs predate 'turbo' plugs by a considerable  time margin-a decade or more-and were developed for aero use, 'turbo' plugs were developed for the RC car buggy and truck engine market and subsequently expanded into aero use. Nelson plugs come in only 4 types-standard, heavy duty and hot-plus the globee insert types, turbo plugs come in an almost bewildering range of heats-7 or 8 heat ranges from some manufacturers.

Conflating the two types as 'Nelson turbo plugs' only serves to muddy the waters-particular for people with less experience

ChrisM
'ffkiwi'

Sorry if my post was disturbing..It is only semantics though...if all Nelson plugs are turbo type - in a sense that they help increase engine power with their tapered seal, not allowing compression impairment between the plug and head threads -  then calling them turbo plugs like the later turbo plugs should not be misleading, let alone, muddying. I for one did not know they all are turbo, thought they also come as "straight" plugs  with no tapered tip, but did not check..

Thank you for the clarification Chris...we all learn here from each other.

balogh wrote:Sorry if my post was disturbing..It is only semantics though...if all Nelson plugs are turbo type - in a sense that they help increase engine power with their tapered seal, not allowing compression impairment between the plug and head threads -  then calling them turbo plugs like the later turbo plugs should not be misleading. I for one did not know they all are turbo, thought they also come as "straight" plugs  with no tapered tip, but did not check..

semantics ARE important-as any lawyer will tell you. No, Nelson plugs have always been of their current form-and its only relatively recently that the 'hot' grade one was added to the range-early on there was only the standard and heavy duty models...and you're doing it again-calling them 'turbo'-the very point I made earlier that you shouldn't conflate the two distinct type-they're not 'turbo Nelsons-they're just 'Nelson'....otherwise down the track you'll get some twerp trying to screw a Nelson plug into a turbo plug head-or vice versa..because they think they're the same thing! And with a different thread, and different cone angle...how do you think that's going to work out...?

ChrisM
'ffkiwi'

Sorry Chris please, my language is not native English, so allow me to be less sensitive to English linguistic differrences...I do not think that me erroneously calling Nelsons "turbo plugs" will drive any user to try forcing them into normal, smaller plug holes..they have distinctly and visibly different diameters.

OK-I think I've made my point adequately now....and it would be a case of people trying to force wrong threaded plugs into similar sized holes...11/32"-32 thread Nelson vs M8x0.75 thread turbo-
we're not talking 1/4"-32 plugs here....though in your part of the world there are no doubt still a few 6mm thread Czech or Russian glowplugs knocking around from the early postwar years...

ChrisM
'ffkiwi'

The identification of Nelson plugs was always confusing to me due to the notches on the hex nut and the insulator color.
I knew that the Hot version had  the large filament hole and the Cold had the small filament hole.  
On a recent eBay listing, Larry said that he found out that the notches actually were a reference to a particular type of filament material.
I have some Nelson plugs 20 years old, 10 years old, and apparently new production that all seem visually different.
FWIW Steve..

Henry Nelson told me he still makes the plugs even though he's retired. He doesn't produce engines any longer. I was flying against him in Huntersville and the conversation of the N36 combat engine shifted to plugs. His plug style and type has been copied by many. In order to insure he would sell his plugs, he created a way to produce the plugs quicker and more effective than any manufacturer could. This was in order to keep the price as low as possible. The marks on the hex was used as a identifier for the most current HD plug. The hot doesn't use the notched hex. In the late 90's, he was experiencing some issues with threads being a bit tight and also the glass seals were failing on the post. He changed the process he was using a new method which to identify the newer HD, but it was also another manufacturing step to drive the competition away.