Nelson head,plug

That's the NLO5 hot plug isn't it, the one for throttled engines? I was thinking for CL or non-throttled engines we should use the NLO2 cold plug with the groove cut in the corners of the hex nut.
http://kittingittogether.com/glow-plugs/nelson-hd-plug-nl02/

The NL05 hot plug keeps the reduced methanol catalyzing when throttled back.

Thanks for reminding me. I pulled the head off of my Tarno equiped TD 049 and put it on my tach race engine without thinking about the hot plug.

All fixed now.



Jason

One important factor is cost. The Nelson plugs are inexpensive compared to ANY other plug in the market today. The other note is they're the most reliable. I've subjected these plugs up to 70% nitro and they hold up. Cox plugs fatigue rapidly with 35% nitro especially if over compressed. All F2D and .40 pylon engines are generally running Nelson plugs. Nelson plugs with the Galbreath head adapter in a Cox engine is going to require more head shims than the stock plug due to over compression. The initial investment is the adapter, but the plugs in the long run will certainly keep your wallet satisfied. The Glo Bee head buttons in my opinion put more rpm's in a Tee Dee than any other plug I've ever used. There were several different versions of this plug. There was a racing style more like the 1702 Cox head and there was also a sport version and I recently found another style of Glo Bee in my collection. These were very unreliable. They worked or just stopped working. There were several I had that had great longevity but others failed in under 30 seconds. Kustom Kraftmanship provided the Glo Bee plugs on their engines. Ken

Hot Plug Low Nitro

Cold Plug High Nitro

Matt,

" In general" the answer is yes (increases from 100 - 800 rpm).
In reality the answer is not always, & sometimes your engine will run slower & needle rougher. That's been my experience using the Nelson Heavy Duty glow plug. The Doug Galbreath designed head appears to need more head shims than normal & performance can be way off if the head shimming is wrong for a given engine/fuel/prop combination. The short of it is I've found 4 head shims to be my 'standard' when using Sig 35% nitro fuel & an APC 4.75D X 4 P prop.
Your results may vary using the hotter Nelson plug or a different fuel. I've found that for optimum performance, some playing around on the bench is often necessary... Good luck!

Cheers, Paul

Matt1967 wrote:In general, will the Nelson increase rpm's over the TD Hi Comp head?

Paul, thanks for answering my post directly

The nelson head increased the RPM on a TD 049 by about 800 RPM using a Cox Grey 5x3 prop and SIG champion 25% fuel. This was above the medium insert head and the cox high compression head which ran about the same RPM.

IMHO final performance is a matter of timing:

For given atmospheric conditions (altitude, temp, humidity) you should pick a prop for the particular airframe and adjust fuel and combustion timing (combustion chamber shape and type of plug...or glow head, and shims) for best performance. Initial settings can be obtained on the ground but final results can only be obtained when the wings hit the wind. As your prop unloads you will see the final timing. Of course if you switch props it will affect final performance.

Write down ALL options so you can recreate them under similar conditions.

The higher the performance, the narrower the peak. For many of us "ballpark" is close enough.

Above all, have fun.

George