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av8tor1977 10-01-2008 03:31 PM

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Hi guys,

I figured I would post this for us to have in the archives. When people ask "What the hell is Gas/Glow", etc., we can refer them to this page and save a lot of typing! ;) If you guys think of anything I should add, just let me know.

Gas/Glow is a unique way of setting up your gasoline airplane engine to run without a spark ignition system. It uses a custom mix of fuel, and a glow plug for ignition.


Lighter weight and cheaper than spark plug ignition.
One less battery to worry about and less equipment space used up.
Most engines gain about 200 to 300 rpms in power.
No radio interference issues.
Easier starting and a smoother, slower idle.


Having to mix the Gas/Glow blend of fuel.
Having to run your engine dry and use after run oil after flying.
Slightly higher fuel consumption.

How it's done:

First, you should verify the condition of your engine. Gas/Glow will not magically repair an engine that needs rebuilt. Note that the spec for ring gaps for most of our engines is around .003", which is a very tiny gap. Larger gaps than this will cause a loss of power, and very much larger than this can cause starting and tuning problems.

REBUILD your carb if it is used.

Buy a "Glow Plug Adapter" available through Horizon Hobby (and others) originally made for running Zenoah engines on alcohol and with a glow plug. If you are handy and careful, one can be made out of an old spark plug, but since the adapter sells for only 10 bucks, I don't recommend it.

Buy an OS Four Stroke glow plug.

Buy a gallon of 10% oil, 10% nitro glow fuel. READ that again please, it is 10% oil, and 10% nitro. This fuel is made by all the major fuel manufacturers, and is commonly called "Glow Fuel For Large Super Tiger Engines." If you absolutely cannot find this fuel, you can create its equivalent by using 20% nitro, 20% oil glow fuel, and cutting it one to one with pure methanol. (One gallon of the 20/20 glow fuel to one gallon of methanol.) Methanol can often be found in automotive speed shops or at go kart racing suppliers.

Mix this fuel with HIGH TEST gasoline in the following ratio: ONE part of the glow fuel to TWO parts of the high test, (premium) gasoline. This will give you your Gas/Glow fuel mix, and it ends up with oil at approximately a 32:1 ratio. You do not need to add any more oil.

Install the glow plug adapter and the OS four stroke glow plug, and open your mixture needles about one full turn more than normal for gasoline use. On most carbs, this will be about 2 1/2 turns open for each. Fuel up with the Gas/Glow mix, apply glow power to the plug, and start the engine. It will likely be rich at this point. Leave the glow power on and let the engine warm up for 3 minutes or so. If the engine is really slobbering rich, lean it some, but don't get serious about tuning until the engine is fully warmed up. Once the engine warms up, adjust the mixture needles to a slightly rich setting. Now you can disconnect the glow power, and finish tuning as normal. You will probably notice that the idle mixture will need to be a touch richer than normal for good transition from low to high throttle.

When you have it all dialed in, mount the engine on your plane and GO FLY!! :D
Since your fuel now has methanol and nitro in it, I highly recommend that you drain the fuel tank, run the engine dry, and inject some after run oil in it after you are done flying for the day. (I just use automatic transmission fluid for an after run oil, and have had great success with it for many years.) Only use fresh, clean glow fuel and gasoline. Containers of glow fuel left open quickly go bad!

If your engine is brand new or rebuilt, it might ruin a glow plug during it's initial break in runs of the first couple of tanks of fuel. Most of us use an old plug to do the initial break in, then install a new OS four stroke plug for final tuning and flying.

In a very few cases, we have found that some carbs won't richen up enough to run the Gas/Glow mix. If you can't get your mixture rich enough, and you KNOW that your carb is in perfect condition, then take off the regulator cover, raise the regulator lever about .010 to .020", and try it again.

We have engines running this system for several years now, and in sizes from 15cc up to over 50cc and in many different brands.

Now, we are more than happy to help you here in the forum. But I ask just one thing. Try the setup EXACTLY as described above. Make no deviations. Then if/when we need to help you trouble shoot something, we are all "on the same page" and working with the same system. This will save a lot of grief and everyone's time. If you deviate from this setup, you are creating a new experiment and that's great, let us know how it works. But for us to help you with THIS system, it needs to be setup exactly as described first.

The reason I say this, is often times we have people ask for help, and after many forum exhanges and a lot of wasted time, we find that they are using a different fuel, have a worn out engine, have the wrong glow plug, are using ethanol instead of methanol, etc., etc., etc. If the engine is set up as described above and tuned properly, the system does work, as proven by our experiences with many engines over several years time.

Let us know how it turns out, send pics, and enjoy the looks of amazement you will get at your flying field or club meetings!!


48cc twin made from two Echo 23.6cc engines, running on Gas/Glow. Red tube and needle valve on firewall are for impulse pump type smoke system. Aircraft is a GP Giant Big Stik.

av8tor1977 10-01-2008 05:15 PM


1. How do I make my own glow plug adapter?

I have gutted spark plugs, bored out the i.d. and then brazed the end of the plug closed. I then drilled and tapped the brass for the glow plug, which should be even with the bottom of the plug for best results. The brass also needs spotfaced inside for the gasket surface of the glow plug. The shell of the plug gets very thin, and it is a pretty involved process for a part that can be bought for only 10 bucks. Note that it also requires a special 1/4 x 32 tap to make one.

2. I can't find the glow fuel. Can I use another?

Basically no. A glow fuel with more oil disrupts the overall percentages of methanol and nitro in the mixture, and also ends up with too much oil which could cause carbon build up in the engine. If you can't find the glow fuel, find a source of methanol and mix it one to one with 20/20 glow fuel. This ends up even cheaper in the long run actually.

3. My engine misfires, what's wrong?

The Gas/Glow engines have a slightly different sound to them when too rich. Misfiring is often a too rich mixture, but also can indicate a bad glow plug.

4. My engine is hard to start, is this because of the Gas/Glow setup?

No. Gas/Glow engines start even easier and idle slower reliably than their conventional gasoline/spark ignition counterparts. If everything is set up and tuned properly, hard starting is then probably due to a worn engine.

5. My engine starts backwards, what do I do?

The Gas/Glow engines will start backwards sometimes. If you slap at the prop to start the engine, they will often kick and start backwards. The cure usually is to develop a good follow through stroke on the start, or use an electric starter. If the engine is well tuned, and you know it well as to what it likes in the way of choking, throttle position, etc. to start, you can also try the "back flip against compression" method of hand starting.

6. Can't I use a different glow plug?

Yes and no. Some of our members have used different glow plugs with varying degrees of success. I highly recommend that you get the setup running properly with the OS Four Stroke plug, and then experiment with other plugs. We have had members report all kinds of strange tuning problems, that all disappeared when they installed the proper glow plug.

7. Will this work on all engines?

While we have obviously not tried the system on every engine made, we have yet to find an engine that wouldn't work with the system. We have the system in use on everything from specially modified Super Tiger .90 engines to engines with over 50cc.

8. Do I HAVE to run it dry and use an after run oil?

I highly recommend it. Just like a glow engine, your engine will have methanol and nitro in it. The methanol draws moisture from the air, and nitro when combined with water and combustion by products can create nitric acid. I don't want any of that left in my engines over night, and therefore run the engine completely dry and use auto trans fluid for after run treatment.

9. Should I run an onboard glow system?

It is not necessary, but one could do so for added reliability and convenience if desired. The engines usually idle slower and more reliably on Gas/Glow than they do normally. Sometimes it is hard to kill them with low throttle, because they just sit there "ticking away" so slowly that you can almost count the prop blades going 'round.

10. I have my engine tuned absolutely perfectly, and it ran on the test stand to my satisfaction. But when I go to fly it, it hesitates, or stumbles, or in general doesn't seem to be in tune. What is wrong with it?

Probably nothing. Gasoline engines have a lot of thermal mass, and take a while to warm up. This is even more true with Gas/Glow engines due to the cooling effect of the methanol in the fuel blend. While you were tuning and playing with your engine setting it up, it (hopefully) fully warmed up. But when you go to the field, fire the engine up, then go to fly, it hasn't had a chance to warm up. I give mine at least a two minute warmup at part throttle and then a full throttle blast for a bit before I fly the first time of the day. (Two minutes can feel like a long time standing there waiting; best to check your watch or you'll probably underestimate the time.)

11. I can't get the grin off my face from seeing the shocked look on all my friends faces about this engine, what do I do?

Enjoy it!! Grins can sometimes be hard to come by these days..... ;)


foamcut 10-01-2008 06:55 PM


Thanks you for consolidating this into a an easy to follow instruction set.
Your efforts to develop this system (along with others) and your continued efforts to educate are greatly appreciated.

I've saved this post as a set of instructions for my own conversion efforts.

Thanks again

av8tor1977 10-01-2008 07:26 PM

Thanks! It took a bit of time and thought, but I figured it would be worth it.


clocknut 10-01-2008 10:48 PM

Hey gas /glow works for me.I followed the thread and I now have A 40 cc running and flying great on my 14 and A half pound road runner and yes everone is watching and asking questions.Its great and I love it.
thanks everyone that made this possible.

aero nut 10-01-2008 11:48 PM

Hey Bob!!!! fine job of putting togheter a synthetized way of learning the ropes on GAS/GLOW , you have said it all in one summarized simple way, maybe we can start a FAQ for Gas/Glow and try to help every one the new converts.
Again CONGRATULATIONS;) are you comming to Tucson for the shootout??? maybe we can meet there I would like to meet your Bro and yourself.
Happy flying and landings.
Your buddy from Tj.
Bill Pomplun

JohnF 10-01-2008 11:56 PM

AV8TOR, This is great stuff! How about adding the 4-stroke set up?

av8tor1977 10-02-2008 12:47 AM

Sorry, but I don't have any experience with four strokes on Gas/Glow. Anyone that does, please speak up!

Yep, I'll be in T town for the shootout. We'll hook up. E-mail me later.


mikenlapaz 10-02-2008 01:50 AM

A thread that needed posing, Thanks

av8tor1977 10-02-2008 02:57 AM

Thanks for all the "kudos" guys, I appreciate it. Hope the post(s) turn out to be very useful.


JohnF 10-02-2008 07:21 AM

AV8TOR, You helped me a lot with my B&S 40cc, 4-stroke conversion. Most of the things that were done are the same as for the 2-stroke however I am using 30% nitro for cars because I don't need or want a lot of oil in the fuel mix. This is due to the Briggs having a wet sump oil system. The thing people have to be aware of is the carb diaphragm. Some will distort because of the nitro and this is true for your 2-stroke conversion also. I am also using a external pulse line and you told me about putting a spring in the pump which on this engine made a big difference. I am not an expert like you so I do not feel qualified to offer a comprehensive list of conversion instructions but for anyone who is interested in my 4-stroke conversion to gas/glow they can do a search on Briggs & Stratton 4-stroke recipe for success. Thanks again for your help and passion for the hobby.

nitro joe 10-02-2008 09:19 AM

Nicely written.
You may want to summit an article to one of the mags.

av8tor1977 10-02-2008 12:54 PM

I did have two articles published in RCM years ago, and I've had some published in ultralight airplane mags. Just can't seem to get myself to sit down and write more articles to publish. One of these days....

Every time I think of something, I add to the original posts above. If I keep at it, it will end up being a book! ;)

Thanks again guys,

buck1856 10-03-2008 01:09 AM

Nice job av8tor.I like it a lot better than the original.

av8tor1977 10-03-2008 01:41 AM

Thanks Buck! It's supposed to cool off in our corner of the world this weekend. I hope so, and I hope it lasts!! Around about now is when OUR flying season really starts...


buck1856 10-03-2008 11:10 PM

Yup,the high here in superior is supposed to be 84 tomorrow.79 on suday with a little rain.Probably a few spits here and there.In about 3 weeks is when our club has its fall fly-in with a bbq to welcome the winter visitors from the North Country.Plus the first weekend of november is the annual big rc auction at the AMA field in Mesa.Another BBQ i hope:D.

av8tor1977 10-03-2008 11:44 PM

Keep me posted, maybe I can come to one of them. I've been spending most of the summer with my brother in Tucson. I'm back in Penasco at the moment, but will probably go back to Tucson next week.


buck1856 10-04-2008 12:14 AM

Sure will.The auction would be the best.Theres usally 35 dollar tables and less setup,plus the auction,ect...We also have a few people[dozen or 2]selling stuff at our flyin.If this economy doesnt get better im selling some of my stuff also.Ive already been selling on an auction site.My buisness is failing right now.Got to go put in an application on tuesday.Oh well,the internet and conversions are saving me right now.

av8tor1977 10-04-2008 12:25 AM

Wow, sorry to hear that Buck. I know, it's hitting me hard too; I guess everyone. I sure hope things get better soon.

Do you have my e-mail?


buck1856 10-04-2008 08:45 PM

Ya,my biz is home remodeling,turn key for realtors,and for private homeowners.Wich,the private ones,my regular customers are the only ones that have been saving my arse.And the auction site.Anyway,PM me your email addy.I should be getting a flyer anyday now from the AMA field about the big auction.2 years ago there was a 35% extra,ARF,all put together.Nothibg wrong with it.There was only one person that bid on it because of the size,plus the money was going to the club as a donation.Went for $200.00.I would have bid on it but i had already bought an Original Byrons 101 inch T-6,fiberglass fuse,wings,vert&horiz stabs,fiberglass cowls.Wings and all where already built.$250.00.

wanafly2mch 10-06-2008 11:04 PM


buck1856 10-07-2008 12:01 AM

Sure,theres a person here in this forum that put one on a 25cc homelite i believe.Captn,was it you maybe that has one on somthing.Maybe he will jump in or know the person im talking about.

av8tor1977 10-07-2008 01:38 AM

Yes, it was Captain John that experimented with using a glow carb for a bit.

Basically, I personally don't recommend it however. In order for it to work properly, you would need to use a pump of some sort. (The Walbro carbs have a built in pump.) Also, most of the glow carbs are too small for our larger gasoline engines. The Walbro carbs are really pretty hard to beat...


captinjohn 10-07-2008 08:07 AM



ORIGINAL: buck1856

Sure,theres a person here in this forum that put one on a 25cc homelite i believe.Captn,was it you maybe that has one on somthing.Maybe he will jump in or know the person im talking about.
Yes it was I who used a Glow carb off a .90 Supertiger. A carb off a .60 or .75 should work also. The reason I tried one is because at the time I had many on hand and not many good Walbbro carbs. I agree with AV8tor, a Walbro carburator is best in most installs. There are some things I do like about the Tiger carbs though. They can be adjusted for mid range and seem to me to adjust quite easy. Then again I have been using them for 30 years!!! I think if a 2 0z head tank was used very close to carb in conjunction with a main tank the glow carb would work better yet. Pressure from exhaust would need to be used to shove fuel from main tank to 2 oz hopper tank close to engine carb. I will do more testing on that later, when I get back from Marquette. Best Regards Capt,n;)

av8tor1977 10-07-2008 12:08 PM

Careful with that.... Using muffler pressure on a gasoline engine makes me nervous. One spark or piece of glowing carbon gets to the fumes in the gas tank and boom! If you want to use a glow carb, better to use a pump such as a Perry, or maybe one made from a Walbro carb like we discussed before.


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