RysiuM.... very interesting work.... keep it coming

I have run very simular tests with glow driver and volt meter attached with a 25cc Homelite engine on glow/gas. With no mufler attached...idle was about non-existant. The engine needed a muffler to hold some heat in for idle. If I turned glow driver up...its fine on idle. With muffler idle was only fair....and engine would quit without golw driver help. I did take some tinfoil and wrap top fins so engine would run a little warmer at idle. That helped a lot. I am going to place cylinder in my Lathe and reduce fin area on top fins near glow plug. I did that first on a scrap cyl...its easy. So I got to do a runable one next. Capt,n Added cut down cylinder

Capt,n I don't think this trick will work here in California. Gas engines burn much hotter than glow, therefore the cooling area is needed (especialy when there is over 90F out here). My "no muffler run" is a description of the sound , not that I don't have any muffler at all. I'm using gutted original muffler as you can see on the picture. It works for holding exhaust close but does not restrickt it and of course doesn't reduce the "puf-puf" sound

The main problem I have so far is the engine missing from time to time even with the glow plug powered - obvious symptom of the wrong mixture setting. And this causes the engine to shake a lot making fine tunning even more difficult (I need to watch my fingers ). Working whole week I will be able to do some adjustments and testing next weekend.

That same misfire you describe is a problem I had in early testing, before I added methanol to the mix.

Good luck with the experiments,
AV8TOR

Hmm... got me thinking. I didn't have this before, when I started this experiment a year ago - same engine, same fuel. Adding the methanol works like increasing the fuel octane rating and slowind down the flame. Maybe I have pre-ignition now. For sure it is not the same "pinging" sound I had when I tried a fuel with 5% nitro.

the pinging sound most likely is doe to low octane gasoline no tso much to the nitro content.

This question has probably been answered already, but, how long will this 2:1 gas-st glow mix keep once it has been mixed? Does it try to separate?

I have had no problems with it separating after sitting for weeks at a time... After a while the gasoline will go bad, especially if it is exposed to sunlight and heat. If/when it starts smelling funky, throw it out or put it in your car and mix a new batch.

When flying the two stroke engines in the Ultralight Airplanes, I had a personal rule that I wouldn't fly with gasoline that had been mixed with oil for more than two weeks. A lot of people fly gas that has been mixed for a month with no problems though. Once the gas has been mixed with oil, it slowly starts going bad however, and it's something to watch out for with any two cycle engine. But these little engines we are using for model airplanes are much less sensitive to octane, and if the gas doesn't smell bad, it should be fine to use.

AV8TOR

Maybe it is my problem, because the fuel I used is 92 Chevron gas with Motul 800 oil mixed about half year ago. I was running the same setup and the same fuel before and I didn't have any problem with engine missing.

What about using 100LL aviation fuel - is it any good for us? I know it is leaded fuel, but does it have any impact on the glow plug?

I have used gas/glow that was 3 months old with on problem.
It was Chevron gas.

AV gas has a fair amount of tetra ethyl lead in it. Enough that your glow plugs won't last very long. The TEL will poison the platinum and kill the catalytic capability.

Yeah; stay away from AVGAS. It has lead which is no good for two stroke engines in general and glow plugs in particular. It will also cause more carbon build up in two stroke engines.

AV8TOR

Well, I've looked everywhere and can't find Super Tigre fuel. Tower only has four-gallon cases and my LHS said it would take 2-3 weeks to get a gallon in. (at least they were honest about it this time.) Methanol, however, isn't a problem. Guess I'll get a gallon of cool power 20/20 heli fuel and cut it. It has a high viscosity syn. lube. Anyone tried this?

I haven't actually tried it myself, but it should be fine. I think some of the guys in this thread have used that before.

Just remember that alcohol is hygroscopic and will absorb moisture right out of the air. Keep your fuel tightly capped, and don't leave your alcohol nor your mixed fuel open for any longer than necessary.

Have fun,
AV8TOR

I think I found the problem. This is not exactly the same engine when I was running Poulan the first time. I tested gasoline with glow plug on my Poulan 25 with magneto still attached. This one is cut to run without magneto. I remember I also lowered the cylinder a little for greater compression (now I understand why my started can't work it out). Like AV8TOR wrote, methanol solves he problem with "overcompressed" engines. So alternative solution would be cutting some spacer for the cylinder to bring the compression back to the original range.

The stuff I got from Tower has been discontinued.
When I went to get the info for you I found it was 10/08.
I was told it was 10/10 when I bought it.

that puts your oil content at 2.6%, or about 38 to 1, right? Should still be plenty of lube with a lot less mess.

I have a US 35 that just needs something to do.. I have looked back at this post and I would like to try this out.. but I see there are allot of ppl having brobs with it. I have having treble finding out all I need to do to make my us 35 gas/glow. From what I see I need to mix 10/10 st fuel with 93 ot gas. What is the 10/10 meen? and what do I ask for from the hoppy shop. I see some ppl is haveing a hard time finding the fuel.. That suks...
then I put a glow plug kit in.

Now do I have to do any thing to the carb. or is my carb on the 35 good.

I don't want to make you all say the same thing over and over but there is 53 pages on this post and it would take me for ever to read it all to find what I need for this....I have tryed and just was getting lost lol

Thanks for the info
Paul

Here is one condensed answer:

Fuel: Any glow fuel mixed with gas, that will give you final proportions: 3% oil, 3% nitro, 30% methanol, 64% gasoline 92 oct. The easiest way is 2 gallons of gasoline, 1 gallon of glow fuel containing 10% nitro and 10% oil (the 10/10 thing). You can use other fuel but mixing is more complicated (requires pure methanol) in example: 2 gallons og gas, 0.5 gallon of methanol, 0.5 galons of glow fuel 20/20 (20% oil, 20% methanl). This proporton is "rule of thumb" but may require some changes depends on your engine (in example my Poulan 25 doesn't like nitro at all)

Carb: use the same orygnal carb, but it will require readjustment on low and high end needle. If you can tune gas engine, you can tune this one too.

Glow: Glow adapter with glow plug in place of reglar spark plug. Use OS F long (so far the best reported). Put power (igniter) to glow plug only on startup. Once started the engine should run like any other RC glow engine without power to glow plug attached.

WARNING: When hand prop (starting) be aware, that if the engine has other than rotary vale carb (reed valve or side mounting carb), the engine might start and will run in the opposite direction (turns into pusher). IT IS VERY DANGEROUS. Be warned.

Ok now that sounds like it will be a ez Engine Conversions. but I just 2 questions to ask

Were can I get a Glow adapter, and what is a good brand of fuel that is 10/10 and how hard is it to find?

That I think should all I need to know before I take my shot and making this work and have a grate time doing it.

Adapter: A couple pages back there is a name of the store - Horizon, or something like that.
Glow fuel: There is no good or bad. Like I wrote 2:1 on gas and 10/10 is starting point. You can try anything. It's all this threat is about

back to my experiment.

I finished the spacer for cylinder in my Poulan. Now it is in the same position as before about 0.8mm higher. Also I modified my test stand to include all equipment (Amp- and Volt-metter) and variable resistor-wire. I found some 0.3mm piano wire that allows me to drop the current below 0.4A - the point where the current that measures glow plug's resistance doesn't heat it any more (31 mW). I added more measurment points to OS F characteristic (the picture below). At the same time I found very BIG PROBLEM in my setup.

When I started my measurments, the results were way off, compared to values taken a couple days ago. The glow plug resistance was over 500miliohm higher [X(]. Then I found, the connection on glow plug "cup" (connector) was not 100% solid. It is a spring loaded connector and obviously contact is not good enough. If I use it all of the precision controll from with Nelson's driver will go south. I have to fix my plug connector so it does not introduce any resistance into the circuit.

Try this guy, http://www.genebarton.com/

He is the least expencive that I've found and has a good product.

He makes them in aluminum and steel.
I bought the steel because I thought it would allow the glow plug to
retain their heat better.

Tell him Ralph Sent you.

bummer.. The only fuel I can find is fuel that is 10/17 Now would that be to much oil?

from what I finding is that I can not get 10/10 with out geting 4 gl at a time.. I think that will be just to much for what I need.. I have been reading back to see what other kinds of mixes that has been tryed. Not finding much on this post.. Playing with this con of conversion are fun put can be a pain in the but if the stuff you need cant be found [:@] but it is still fun to do.. I can get fuels like 10/17 and 15/17 all day.. I would like to know if any one has tryed thes fuels and how did they work and did they work.....

The one thing I cant find in the post is that we need to run hi grade gas.. Is that just the 93 that you can get a the pump or gas like rasing fuel..

I picked up my glow plug Adapter to day. Now if I can just get my fuel right I should be set lol.. but to do so i have to bug you all.. sorry about that..

Paul

No problem...AV8TOR can get you on the right track!!!