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.
Pros:
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.
Cons:
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Buy a "Glow Plug Adapter" available through Horizon Hobby (and others) originally made for running Zenoah engines on alcohol and with a glow plug.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!! 
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!!
AV8TOR
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.