I have been using Fox long standard glow plugs on my three engines but have been having a problem with the engines stopping as soon as the glow starter is removed of stopping a few seconds after the starter is removed. I just got back into RC and I used to use Fox and Tower plugs all the time but never had this problem before.

The engines I am running are a TT Pro 46, a TT GP 40 and an OS Max FP 25. Fuel isOmega 10%. I did a search and the OS A3 seems to be well thought of. What plug would you folks recommend?

Could be the plugs are bad or the fuel mixture is off. If the have spark (glow) and fuel they gotta run.

Old fuel will do this

In my post I stated I just got back into RC. The fuel is brand new.

The OS "F" plug is really good (and expensive). It is designed for four-stroke engines, but works really well in 2-stroke engines as well.
Too rich a needle valve setting can also cause this.

My 2 strokes run well on K&B idle bar medium range plugs. (perfect for your pro 46) My 4 strokes all have OS 4 stroke plugs.

As long as the filament is physically intact, i.e. a complete circuit, you can start an engine with plug heat no matter what the condition of the plug. But is the surface of the plug is "poisoned", i.e. the catalytic surface chemistry is masked by deposits, then when you remove plug heat and ask the engine to continue to run on the catalytic action of the element, it will at the least lose rpm, and at the most quit.

That said, I don't at all disagree this could be a mixture or other issue, but I thought I ought to point out that a classic symptom of a bad/tired plug is rpm loss when plug heat is removed.

rayshooter - are the engines at idle or wide open when this happens, or does it matter? What happens when you do a pinch test at idle? Is the top end mixture set 200-300 rpm below (richer) than peak rpm?

In the winter time the engines have to be set richer on the ground as they go more lean up in the cool air when you take off.

Cool air is more dense and requires more fuel

Quote:

ORIGINAL: ratshooter

I have been using Fox long standard glow plugs on my three engines but have been having a problem with the engines stopping as soon as the glow starter is removed of stopping a few seconds after the starter is removed. I just got back into RC and I used to use Fox and Tower plugs all the time but never had this problem before.

The engines I am running are a TT Pro 46, a TT GP 40 and an OS Max FP 25. Fuel is Omega 10%. I did a search and the OS A3 seems to be well thought of. What plug would you folks recommend?

The TT .46 Pro needs a long-reach, medium heat plug.
The OS #8 is medium heat, but it is too short (medium-reach) and too damn expensive... The OS LC4 will do the job, as well as many others; including the K&B-1L.

The TT .40GP is much like the OS FP/LA engines and will run better with a hotter glow-plug. OS long-reach LC3 is a good choice.
I am not sure about the plug thread-depth of the OS.25FP, but it also needs a hot plug.

And BTW, the OS A3 is no longer... OS now make the #6, which replaces it.

Some places are still calling it an A3 plug, and they are packaged that way.

I bet the problems is caused by the low end is set too rich and not the wrong plug. You said it was a long time since playing with rc, so maybe it just takes a little practice to get back there and get the engines set correctly. Have you done the pinch test at idle?

I've seen this several times when guys revive a long stored engine. Once started, it runs fine till the glow starter is removed, then it runs like crud or stops. The glow plug filament is intact, and they see it glow so the guy rules it out as the cause of the problem. They blame the fuel even tho it's fresh, then try someone else's fuel and still no joy. A fresh plug is suggested, and the statement " It's OK, I saw it glow" followed by "Just humor me and try a new one". End of problem.

As MJD suggested, it may be poisoned or in some way unable to sustain a catalytic action.

I knew someone would come up with some recommendations for glow plugs. Thanks Darzeelon. I just wanted to know what everyone else was using successfully.

I do know how to adjust my engines. I used to get to adjust everyone elses engines and I haven't forgot how to do it. I didn't know you could still buy K&B plugs. I thought K&B was long gone. Long ago I would also buy plugs from Hobby People and they worked fine. I think they were called Glo Bee but I am not sure.

Once again everything I have is brand new and hasn't been stored and revived.

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The OS #8, too short/expensive or not, usually works very well in the TT46 when using fuel with 10 to 15% nitro. My brother fought his engine for a good while using Tower plugs, which some say is really an A3. He put in a #8 and it started running well.

Mecoa sells K&B https://shop.mecoa.com/shopdisplayproducts.asp?id=81
The 1L is $4.99 and they offer discounts if you buy a dozen or more.

Fox Gold.  OS 8, Enya 4, K&amp;B 1L, and many more.  Actually the Fox RC should have worked, but just a tad cold.

I've had good luck with McCoy #59 plugs in all of my engines including my TT .46 Pro. I've had gelled oil take up space in the very top of the glow plug which would only light 2 or 3 coils. I cleaned out with acetone and got all of the coils glowing again and ran the plug for another half gallon.

Quote:

ORIGINAL: ratshooter

I knew someone would come up with some recommendations for glow plugs. Thanks DarZeelon. I just wanted to know what everyone else was using successfully.

Ratshooter,


An engine's designed compression ratio, fuel type (nitro) and load, determines the heat-range of the plug it needs.

One can use a hotter plug, but the mixture setting will have to be richened.
The engine will then seem to run fine, but its fuel consumption will drastically increase.

This certainly is not considered by me, to be 'using successfully'.

A colder than recommended plug, will not allow the engine to run well over most of its range.
Nitro may be increased to overcome this, but this also will increase fuel consumption.


I strongly suggest that the correct heat-range of the plug is adhered to.

EDIT: Language.

Thanks for the replies guys. The chart helped also. I think I will pick up some medium range plugs and give those a try. The best plug I have used so far has been the one that came with the TT Pro 46. I just can't find anymore. And like I said everything I have is new and still being broken in so I am running a little rich still. The FP 25 was a used engine I bought off ebay. The TT plug really cleaned it up and got it running. Plus the spray bar wasn't screwed in far enough and it would lose vaccum and die. Two more turns in fixed that.

I use OS "F" Types as well on my two strokes, especially the big ones, just like having an on board battery..!!

I ordered two #6, two #7 and six Tower plugs. Thart will give me enough to experiment with. Thanks for the info and suggestions.

Quote:

ORIGINAL: ratshooter

I ordered two #6, two #7 and six Tower plugs. Thart will give me enough to experiment with. Thanks for the info and suggestions.

RS,


The #6, being 'hot' will work; but as I previously stated, it is medium-reach (as are the OS #7, #8 and #10...) and thus too short for a proper, flush fit into your engine's combustion chamber (it does not properly fit most OS engines either...).

The TowerPower, which is the current offering from them, is a clone of the OS #8 (the older Tower plug was an A3/#6 cone), so it will be a bit too cold for your Evolution engine. It is also medium reach, BTW.

Once, glow-plugs were literally 'a dime a dozen'...
One could buy them really cheap and they could be considered expendible.

But this is no longer the case. Plugs are now expensive.
The price of an engine will now cover, with many Chinese engines such as your own, only 6-15 glow plugs of certain brands.


The way to buy a plug today, is to ask (in this forum, for instance) what you need and then to buy only it...
Experimentation is rather wasteful... as is running your engine richer than it needs.

You asked, but then bought what you felt like; not necessarily what is best for your engine.


Your engine's break-in was completed after just two tanks [link=http://www.rcuniverse.com/forum/m_1850473/tm.htm]rich two-cycling[/link]. There is no point it running it richer than necessary any longer.

<font color="#000066">"The TowerPower, which is the current offering from them, is a clone of the OS #8 (the older Tower plug was an A3/#6 cone), so it will be a bit too cold for your </font>Evolution<font color="#000066"> engine. It is also medium reach, BTW"

I never said I own an Evolution engine and I don't. Experimenting is part of the fun. I used to use tower plugs and they did just fine in my GP 42s and 46 FX. I think the medium and hot plugs will help with what I am running.

As far as cost goes that really isn't an issue either. Once I find what works I will buy a bunch. I just don't want to spend money on plugs that aren't right for what I am running. Thats what gets expensive.
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I don`t know what you pay for plugs in the US, I order them from Hong Kong as I do with most of my hardware. I like these and use them in several engines, bottom of the page and the next page: http://www.himodel.com/sort.php?sub2=CK not expensive at all, I use the ASP general two and fourstroke plug the most.

Oops!


RS,


I somehow got the reply on this thread mixed up with one in a local thread; here in the Israeli R/C site...

...Of course your engine is not an Evolution... No offense intended.

But what I had written regarding heat ranges and thread depth still goes. The TowerPower is too cold for the OS.25FP and also for the TT .40GP.
It should be right in that respect in the TT .46 Pro.

And it is short for both the .40 and the .46 engines.