Cougar429

My Feedback: (3)

Not sure of Fox heat ranges either, although I believe there is info available.

As for OS 2-stroke plugs, I generally ran #8 down into the 30's F range. Below that I either opted for their hotter A3 or even a 4-stroke "F" if it was a bit cantankerous.

Sport_Pilot

The 1L is sort of between a cold and medium heat range. Good for say an OS on 15% or 20% nitro. The heli guys used to like that plug with 20% nitro.

mgoodwin

delete

1QwkSport2.5r

All I've ever seen the 1L advertised as is hot. Either way, it doesn't work well for me here in Minnesota.

I found Enya #3's for the same price as my McCoy's so I may just use Enya plugs from now on.

Now I just need a Fox engine that doesn't eat itself and I'll be set.

Sport_Pilot

I may be thiking of their high performance plug. Found this but no K&B plugs listed.

badger5964

My Feedback: (6)

I emailed Fox about the heat ranges of their plugs a couple years ago, they said from hottest to coolest:P

Fox Miracle, Fox standard, Fox RC, Fox Gold Standard, Fox Gold RC. They described as Super Hot, Hot, medium-hot, medium-hot and medium. Did not ask about the #8.

I almost always run the Fox standard in my Foxes run on 0% nitro.

I bought (12) Fox #8 off of ebay early this year. I was going through a Fox gold plug every other tank on Magnum 25 XLS during combat. I run a 15%, 9X4 prop and a mousse can pipe. I switched to the Fox #8 and am getting long life from the plugs, likely a dozen flights or perhaps more. RPM and idle seems the same. I'd rate this one as a medium-cold or cold plug.

1QwkSport2.5r

I have had really good luck with the McCoy plugs, getting several gallons of fuel to one plug. My Enya ss30 is up to close to 2-2.5 gallons now and is still on the plug it broke in with. I think to some that might seem far off as hot plugs tend not to last as long as a colder plug, but as long as they aren't ran too lean, they survive quite well. Well enough to tolerate a lapped iron/steel engine to break in. Fox plugs are definitely sturdy and robust, but I dont think they allow the engine to perform quite as good. My least favorite plug is the OS F plug. Its sturdy, but a poor performer in my book. I have used OS 6 and 8 plugs long ago, and didnt have good luck with them either. Those were used in car engines running 20% nitro and 14% oil and turning at 38,000rpm.

Cold plugs last longer, and are tougher than hot plugs, but usually, unless you use a lot of nitro, the idle will be iffy. All but one of my engines requires low nitro, 0-5%, so I have to run hot plugs in them. Colder plugs means crappy idle and on an airboat without a return-to-shore system, stalling/deadsticking/flaming out sucks.

K&B 1L is a medium/hot, 1S is the same but short reach. They dont seem to have any hot or super hot plugs. All medium/hot and down to cold range.
http://www.mecoa.com/acc/glowplug/glowplug.htm

Fox is one of the few glow plug suppliers that offers 2v glow plugs. Almost all others are 1.2-1.5v.

earlwb

My Fox glow plugs seemingly last for many hours of usage. I don't change the plug unless I am troubleshooting something. But during break in sometimes a engine will eat a plug or two though. I have had some engines fly all spring and summer, most every weekend, and use one plug doing it. But I do remember for racing where I would use a new plug at the beginning of the series for that day though. Now every once in a while I have had glow plugs die on me when I went to start a engine. So one's luck tends to vary with the glow plugs.

hsukaria

When I was still having engine issues with the Fox 74, if I ran it too lean on high nitro, the plug would scramble. A couple of times there would be a loud crack sound, that is when the glow plug would break the seal and the center electrode would separate from the outer part of the plug. The plug got so hot that the insulation between the inner and outer part of the plug cracked. That was quite dramatic.

1QwkSport2.5r

That is pretty darn hot to get the glow plug to come apart like that. [X(][:-] The only thing I've noticed when an engine gets too hot is it just quits. Then again, I have only used 1 quart of 15% nitro in an engine and that was what... 3 years ago? Maybe 4...

I did collapse an element somehow in my ST 90. I was tuning the main needle down to peak then richening so a pinch raised rpm a little.. and apparently it was a touch too lean. The engine still ran on the collapsed plug, but it didnt glow very well. Thankfully, I have only had an element collapse once or twice. Any other time the engine gets too lean and hot, it just quits. That goes for almost all of my engines.

koastrc

Club Fox is the only thing I subscribe to on the net. I have been out of step for a while with glo-engines. Fox-ST-and Enya. All are becoming rare now, but all still impress at the field. This is a good subject and is loaded with some very good information, Thanks!

earlwb

huskaria, it sure sounds like you had some detonation going on, as the preignition would defintely destroy a glow plug. You are lucky it didn't tear up the piston too. Worst case it burns or blasts a hole into the top of the piston or less worse it breaks off the top support for the piston ring groove.

hsukaria

Yeah, I've seen horror pictures of burned pistons and catastrophic damage in these forums. I never heard detonation in model engines before. So I can't tell you that is what I experienced first hand. But I had to go through a lot of steps to try to correct from help I got in this forum (mostly you and Konrad, among others). I still wonder if my engine should have been that sensitive/hot. I know Fox engines need low nitro and all that, but mine seems an extreme example. I am still keeping an eye on it. Went to 0% nitro, and a smaller prop. to be safe. Like I said before, I might send it to Fox for evaluation. Who knows, I might learn someting.

Cougar429

My Feedback: (3)

I've seen MANY OS 50 heli engines suffer burn through and I have one of those pistons sitting in my spares, (keeping it for the rod, wrist pin and keepers). I also have a YS 50 heli engine that ran extremely hot before I got it and the liner looks like it was hit with a blow torch. Guess 30% heli fuel really cooks these off.

hsukaria, have you modded the head button? Wondering if Fox changed the profile with the newest designs. As posted recently I fried the piston on the Eagle IV 60 in short order and with the new motor tried several different profiles to see how they would work out. Not enough time yet to see how that ends up, but the lowest comp button also seems the less problematic with 15%.

To be honest, in close to 30 years running nitro I have never had a plug failure like you described. It would seem any leaning issue would cause other problems, such as seizing or scuffing the piston.

hsukaria

Hi Cougar,
I have replaced the head button with the latest from Fox. I forgot to mention that. It was the biggest improvement. I also added baffling in the cowl. Everything I could do to help.
Husein

aspeed

Usually scrambled plug elements are from too high compression/nitro.  I have also blown seals from too high compression.  Fireballs are notorious for blown seals, but the element will hold up much better to the nitro.  I would just add a head shim if you are going through plugs, sounds maybe too lean or running hot (I guess heli's are just going to have that problem) When I was racing, the Fox elements got scrambled the easiest, the Fireball cools took the nitro, and the K&B 1L were good all around.  Now there are many more companies in the mix.  Merlin, McCoy etc. It is always good to experiment with plugs, they make a big difference. A cooler plug may stop detonation, as well as adding a shim, which could stop the seal from blowing out..... I blew three seals this year already.

Cougar429

My Feedback: (3)

Oh, Man! that was too easy! Anyone remember the song "Wet Dreams"?

hsukaria, any way to show that newer head button, if even in one of the graphics that have been posted here? Wondering how it would compare to my home grown versions.

hsukaria

You know, I am very bad with that. I kept looking at pictures in this forum and at my own head buttons. I could see a difference, but couldn't tell what the heck it meant. I was trying to determine if the volume was different, but couldn't do it visually. The big difference was the rim around the chamber was actually wider in the new head button. But the curved chamber was deeper. So, I assumed that the compression won't change much. Just the shape of the combustion chamber is now smaller diameter, but deeper. FWIW.

Sport_Pilot

Would you rather he blew heads?

hsukaria

True, better to damage a glow plug. But the sound it makes when the plug blows is startling, to say the least.

hsukaria

Getting back to the glowplug topic. I noticed that sometimes the plug dies on me when I am starting an engine after it had been stored away for a while. I usually flood the engine with ATF if I plan to not run through the winter.

I wonder if the ATF flooding the engine stresses the glow plug when I first put the starter on. I suspect that I should first spin the engine with the glowplug off to remove excess ATF oil?

Anybody have experience with that?

earlwb

I think you are correct, The excess oil is blasting the glow plug and then you fire it up. So the large oil droplets can crush the heating coil element or the contaminants in the oil coat it causing it to fail that way too. I would suggest using a old used plug for that first run to clear the engine out. Then put in the nicer plug.

hsukaria

Thanks Earl. I wish I would have thought about that a long time ago. I would have saved some $$$.

Cougar429

My Feedback: (3)

I've fired up my engines loaded with my 50/50 mix ARO of ATF and air tool oil, either in short term, (from the last flying session) or long term storage and cannot remember ever having a problem. Are your engines mounted inverted?

earlwb

I have had something like that happen with inverted engines, where the oil residue in the engine oozes down over the glow plug element and drowns it out or coats it with something when I use the ignitor on it. The element doesn't burn out, it still glows, but the engine won't even pop for me. But a new plug fixes the problem.