Is there a "big" difference in using a cheaper fox rc long glow plug compared to the more expensive O.S. glow plugs for a .40 - .46 size 2 stroke engine?

I think so. I quit using glow plugs from Fox, K&B, etc... after seeing them burn out too quick. I use only two plugs. I use OS #8's for most of my 2-stroke glow engines and OS "F"'s for 4 strokes and big glow engines. Every once in awhile I will will use the cheap OS A3 in small glow.

Maybe I am paying too much for glow plugs. But these last and I don't have to worry about them.

-Cheech

I use OS "F" for every engine I have. Two stroke as well as four stroke engines. Never had a problem with any of them.

I agree with Cheech but would add the K&B HP plug. I use it on my Webra 32 with mousse can pipe and they hold up better than the OS#8 plug.

Pete

I use OS "F" for every engine I have. Two stroke as well as four stroke engines. Never had a problem with any of them.

I have found that Fox's Miracle plug works very well in all my fourstrokes as well as 2 strokes. I use other brands also but always have a couple of Miracle plugs in my tool box since they work so well on all brands and types of motors.

Yup, there is. I accidently proved this to myself years ago.

I had a K&B 3.5 cc outboard. I used to run it with nothing but K&B plugs. The group I raced with had disbanded so the boat sat on the shelf for a few years. One day I decided I would just bring it with me to the lake while I was out boating. Got it all cleaned up, installed a new plug (not K&B) and headed off to the lake. When I got it running I couldn't figure out why it was so much slower than before. No matter what I did, it just wouldn't unwind right. Not sure why I thought of it, but I pulled the (cheap) plug and installed the old K&B plug. Big difference. From that day forward I stopped buying cheap plugs.

I now only use OS #8 for 2 strokes, OS F for 4 strokes, and K&B on my boat and K&B aero engines.

When I review engines I usually test 4 different brands of plug (various). I have found quite a bit of difference (in terms of top RPM, idle, and transition response) especially bewteen brands like Fox, OS and others.

Personally, In most engines I like the OS #8 and A3, the K&B 1L, the Hangar 9 super plugs and the Tower Hobbies "OS#8 clones"... I find myself using OS #8's in most of my engines. The OS F in 4 strokes still seems to be the longest lasting and without issue.

Just my experience/opinion.

AJC

The "big" difference in plugs is the heat range. This is the equivalent of advancing or retarding the distributor in your car and why I can never understand the blanket statement "use an OS #8" (or whatever) without considering how much nitro is being used or other variables. A hot plug from one brand will be different to a hot plug of another brand so there's going to be a difference in revs. That doesn't mean that one plug is better, it just means it was more suitable to that particular engine/fuel combination. Some plugs (Enya for instance) have a reputation for lasting longer than others but I've found that even some real cheapies can last practically forever.

The basic thing with plugs is that the one that gives the highest revs is the best plug (regardless of brand or heat range).

But, all things aside... like the various plugs in various heat ranges from the various manufacturers:

When you consider that (in North America) 90% or more of the engines are designed to run on 5% to 15% nitro/18% oil and are set to run with this fuel with a medium/warm plug - you will, after testing the various plugs on the market also come up with what works well irregardless of what the plug heat range is claimed to be.

FOr instance, after running dozens upon dozens of engines with many many plugs in my personal experinece its very VERY hard to beat the OS #8 for performance, and durability. When I buy a new engine, I put in an OS #8 FIRST knowing full well it is more than likely going to be the proper plug for the engine. Yes, there are exceptions and in some cases another plug will perform better. But, I imagine most of the readers here are into sport flying with the more common engines available. There are plugs that will run similarly to the OS, but they (again in my experience) do not last nearly as long. Similarly with the OS F and 4 strokes. Some work as well but do not seem to last as long.

In the end, like engines, there are many to chose from (plugs that is) and some may like a Fox, some the OS, etc etc but all We can offer are the real world experiences we have right?

AJC

Not entirely correct IMO speaking about RC engines (not CL or wide open throttle). Plugs can have the same heat range, give similar top RPM readings, but one plug will allow a lower reliabel idle and a better transition over another. I believe this may be due to more or less winds, with varying thickness and metal content of the wire.

AJC

Also please note I am just expressing my own experiences and opinion and in no way am I trying to say OS #8's are the "only" good plug... and I am just adding to the converstation, not trying to argue your own points.

AJC

As we all do and so we should
BTW, I agree with everything you said too. Yes, idle and transition play a part in choosing a plug even if it means losing a little on the top end. The best site I've found about plugs and the affect on the engine for different heat ranges is at http://www.modeltechnics.com/glowplug/firepower.html where they take into account things like idle, transition, max revs before selecting the best plug for that engine/prop/fuel/compression. But even from their results it can be seen that most plugs from the hottest to coldest give acceptable results for a sports flyer.