I am just getting started in the RC airplane hobby and I would like to know if there are any sources of information available on glow plug selection. I am a little confused by the assortment of lengths, heat ranges and types (styles). Being an old motorcycle mechanic, I am familiar with short reach and long reach plugs, heat ranges, etc., but the motorcycle manufacturers design their engines to use a certain length plug and that length should always be used. From what I have observed to this point, glow engines are not that specific, or are they? Do the glow engine manufacturers recommend specific plugs for their engines? If so where can I find that information? To keep things as simple as possible I am only looking for info on 2-cycle engines. Thank you for any assistance you can provide.

....welcome to RCU....I'm an old m/c mechanic myself.
I'll give you the short answer....there are short plugs
for the small glow engines, and long reach for the larger
ones. There are 2-cycle and 4-cycle plugs....and there
are idle bar, and non idle bar plugs.

Some engines come with a plug, some do not....but they
will usually give a plug recommendation.

And there is a wide range of heat ranges available....
but generally they are used in specialty applications,
like racing engines and such. The heat range thing works
much like it does in bikes. Different nitro percentages
can require different heat ranges.

Different brands of engines like certain types of plugs....
like Fords like Autolite or Motorcraft plugs....not AC's.

It can be a trial and error thing....but for the most part....
sport motors like middle of the road medium heat range
sport plugs. Getting a plug recommendation is like asking
a guy what kind of beer he likes.

With the exception of my Rossi engines which use Rossi
plugs I use K&B short and long reach #1's....and Fox Miracle
plugs in all my Sport two strokes. I do not use idle bar plugs
but certain engines actually prefer them.

Dave.

After you're in this a little, you'll discover that the OS 2 cycle long reach plugs are shorter than normal. They are too long to be short and too short to be long. However, the long reach plugs are considered to be long reach plugs and they work very well. The Tower Power plug from Tower Hobbies is also shorter this way.

Enjoy,

Jim

To get back to the question, there really isn't a standard for glow plug sizes or heat. Someone's "hot" plug may be someone else's "cold" plug.

It's tough to figure out which plug to use when you're starting out. You may ask, "Well, why isn't there a website with all this data listed?" That would require someone, one person, to go out and buy every glow plug available, find some way to test and compare them scientifically, compile the data, build a website, and advertise it. That's a LOT of work for someone to do on a VOLUNTEER basis, paying for all those plugs, and the website, out of his own pocket. It would have to be one person, or a carfully organized group. We couldn't just send in reports, it wouldn't be accurate... "Oh I think this plug's hot." Well, what's hot? Even the plug manufacturers don't know. Besides, a community project where there is no clear goal and no reward for the participants is difficult to organize, and even more difficult to sustain. You'll get lots of "I'll help" but when it comes time to do the work or send in the data, forget it...

Anyway, once you get into the hobby, you'll develop a sense for what glow plugs you like. It's a very subjective thing. I've tried probably a dozen different models of glow plugs, and my personal favorite is the OS #8. It's expensive, but reliable.

I agree with Mkirsch's recommendation for the OS 8 plug. In fact, most of the plugs I use are either OS 3 or OS 8 and their higher cost is greatly offset by the fact that they seem to last almost forever.

As for people who strongly advocate other brands, sometimes you just don't know what you are missing until you try it.

Andy

Brew, have you ever entertained the idea that others advocate other brands because they work best for them? For example, if you take a Fox Miracle plug out of a fourstroke and put an OSf in, the engine runs exactly the same, so what is the point. You can't justify using some other brand or type just because it might work better some day.

There is a pretty good article in one of the mags from a month or two ago. I believe it was Model Airplane News, but I'm not positive. Still, it would be worthwhile to check them out and see if it's there. The information was good and gives basic information on how to select the proper plug for your engine with your performance goals in mind.

John

Thanks to everyone for the information. I started out using Fox Standard Long plugs, but have recently switched to OS A3 plugs. I was told that they are a better quality plug. When I expressed concern over the difference in length of the A3 and the Fox STD Long, I was told that either one will work. That is where I began to get a little confused. BTW, I am running these plugs in .40-.46 2-cycle engines. What is the difference between the OS A3 and the OS 8 plugs other than the 8 is more expensive? John, I would greatly appreciate it if you can find out for sure which issue that article on glow plug selection was in. I would like to read it. Thanks again to everyone who took the time to respond to my inquiry. It's great to have have a resource like RC Universe to turn to.

Dirt Dauber,
I'd love to be able to tell you definitively which mag the article was in, but I read it in a mag loaned to me by a co-worker who is currently on vacation. I'm almost positive it was M.A.N. though as I know it wasn't RCM and my co-worker hasn't read Model Builder yet.

John

....It will work just fine in just about anything....

Nah, just don't needle it lean and you'll be fine. Either that or install a VP-20 pump, set the needle and forget it unless the weather changes dramatically. I really do miss that high compression Saito .80.

John

The OS A3 is their hottest plug with the #8 being the next hottest. The Enya #3 is also an extremely good plug and is the same length as the OS plugs (call it medium reach). I believe the Tower Power plugs are just a badge engineered OS

Go to http://www.modeltechnics.com/glowplug/glowplug.html to see the range of plugs from one manufacturer and then to http://www.modeltechnics.com/glowplug/firepower.html to see the results of using different heat ranges in the one engine. This is the best site I've found for getting an idea of how different plugs can affect the performance.

Enya plugs are very good indeed. I've never worn one out even after a couple of years of use in my Enya .53 4-stroke.

John