I had the exact same problem on my JP .21. on another thread the guys suggested running shims on higher nitro. Well i went the conservative way with my .12 TZ and it worked a treat. i added two head shims, ran it on 30% and it screamed and sounded sweet. no weird noises (detonation) and had tonnes of power. ill strip the engine tonight to double check everything tho.

RB does this on their FAQ page. Here is the link to it.
http://www.rbproducts.com/mainEn.php...ght%20glowplug

Hope this answers your question.

Thanks! Should have looked there - I was all over the plug section.

Melting coils = too much compression.

Add 0.1mm shim(s) or use lower nitro content.

What is the difference between F and C on the Nova turbo plugs?

F = Freddo
C = Caldo(sp?)

A C7TF is Very cold while a C7TC is cold.

I only run 7 plugs and the temperature outside determains weather I use a F or C plug.

I also suggest you read this on all the info on glowplugs you will need.

http://www.rbproducts.com/mainEn.php...ght%20glowplug

The numbers and characters on the plugs, are the product number, wire thickness, and thermal range of the plug’s body. Example: The Novarossi C6TG (F) or (C)
Product: C (Conical)
Wire Thickness: 6
Plug Type: T (Turbo)
Plated: G (Gold)
Thermal Range: F (Fredda = Cold) C (Calda = Hot)

The plugs with cold thermal range F (Fredda), have a body with thinner walls and shorter body, so they dissipate heat better and faster to the engine head. The plugs with hot thermal range C (Calda), have a body with thicker walls and longer body, so they dissipate heat better and faster to the engine head. The number of threads is the same on both types of plugs.

How to select the proper plug:
·When the ambient temperature is high, we have to use a plug with thicker wire.
·With higher compression, we have to use a plug with thicker wire.
·Humidity determines if we use a Cold (F) thermal range, or Hot (C) thermal range.
·With high humidity percentage we should use a Hot (C) thermal range plug.
·If we have high temperature and high humidity, we should use a plug with thick wire and a Hot(C) thermal range.

On Another note: The Old OS standard plugs such as the Nº8, Nº5 have fewer threads than Nova based plugs, so they sit higher in the combustion chamber of a Nova based engine, and won't work addecuately, thus your problem.

AFM

Well Done AFM

I would to add another tips to eliminate melting glow plugs.

Increase shim thickness by 0.1mm
Use thicker wire ( colder ) glow plugs ( I prefer this one )
Lower nitro content

I also found out that Long Plug tends to last longer... That's what I've been using.

Before I get flamed, they're available locally, how are MegaTech plugs?

An OS #8 is fine with 30% nitro but you should not use an OS plug in anything but an OS or Go Tech engine. Those engines are designed for "short" plugs. All other engines should be run with standard reach plugs.

How old is your engine? A common cause of engines eating plugs quickly is a worn lower rod bushing. If this is the cause then it should be difficult to get the engine to idle well too.

It was the wrong plug and high %.

How are Megatech plugs?