Thanks for the info. I'm still having to go way lean on the low needle to get a mediocre transition without glow power. It's still not consistant and reliable---I wouldn't trust it in the air. I'm going to mount a switch next to the throttle servo and run power up to about 1/3 throttle. (I'm just ready to bolt the d--m thing on and go flying!)

You'll like it!!

AV8TOR

I read back to page 78 and didn't see what you are running.

I assume you are using 10/10 glow fuel.
You may be a canadate for 15% nitro.
The test is if you remove power and the idle slows more than a couple 100 rpm.

Oil content isn't as important as one might think, as long as there is enough.
If you have 15/18 or something close mix up a small test batch and give it a try.

Running a 33 homelite with 10/10 glow. (actually its 20/20 heli fuel cut in half with methanol). The idle does drop when power is removed. You're saying 18% oil isn't too much? It'll come to 6% in the mix, or less than 17:1. Will that work?

Sure, it will work, but I don't recommend it. Too much oil just carbons everything up; ports, rings, piston, glow plug, besides the mess it makes. If you run such a heavy oil mixture for long, it will eventually freeze the rings in the piston with carbon. Then the blowby gases will overheat the sides of the piston and burn the oil off, and then the engine will seize up. Further, in our case, (Gas/Glow), the extra oil takes the place of methanol, which is needed for the catalytic reaction with the glow plug. Why would anyone want to run DOUBLE the necessary oil?

What some people don't think about or understand, is that a pure glow engine can get away with the extra oil, because pure glow fuel burns cooler than gasoline and the excess oil usually doesn't burn, or carbonize. Gasoline burns hot enough to carbonize excess oil. Even the standard Gas/Glow mix is a touch heavy on oil, I really wouldn't want more oil in my engine...

AV8TOR

i just tryed my gas/glow conversion out!
and i have to say WOW!
first i got my old nitro and mixed it in a 1:3 ratio with the normal fuel.
but i soon discovered it didn't like mixing[&:] how do you get normal gas to mix with 10/10 nitro fuel?

then after the nitro in hte tank was gone i tryed it with just straight gas at a 25:1 fuel to oil ratio.
it ran with this WITHOUT glow power! but it did run cruddy but as soon as i gave it the glow warmer it was just as good as it was gas!
and OOOOOHHHH boy! does it idle SLOOOOOOW only fireing twice or three times every second (but the revs were faster than that).
it was fickle with out glow warmer when running straight gas though.

i cant wait to get some more nitro

so how do you get nitro to mix with gas? or did i miss the fuel chemistery part?

shaun

One part 10% oil, 10% nitro glow fuel

Two parts high test (premium) gasoline

I have had no mixing problems, and I've had the mixture sit for weeks at a time.

One note for everyone however... Gasoline starts going bad the moment you mix it with oil. My personal rule when flying Ultralight Airplanes with two stroke engines is that I won't fly with fuel that has been mixed for more than two weeks. (Most people fly with fuel up to a month old without problems however.) Our smaller model airplane engines aren't as octane sensitive, and will run ok on older fuel, but I did notice my Poulan 42cc running a bit ragged the other day (on Gas/Glow). Then I realized the fuel was almost three months old. I mixed up a fresh batch, and the motor runs fine now.

AV8TOR

18% oil it to much to run all the time, but it's not to much to use as a test batch.
It will simply let you know if your engine likes more nitro.

There are to many variables for this to be an exact science.
You will need to dial in your engine.

I don't know the difference in down under gas and gas here in the state but glow fuel and our gas mix with out any problem.

I've followed this thread from the beginning and your the first to state any such problem.

Hi Ralph,

Yeah, I understand what you are saying about the nitro, and you are right. A drop in rpm when removing the glow plug means an engine could use either a higher compression ratio, or more nitro. The problem with trying the 15/18 fuel for a test however, is that the issue is "muddied" by the extra 8 percent oil lowering the methanol content, which I believe is almost as low as it dare be for reliable glow operation already.

AV8TOR

thanks guys!
i am running premium gas at a 25:1 ratio but maby i should make it 33:1 or less.
also, new nitro may help with the mixing problem.
when i mixed it was fine but after a sitting for a few seconds the methonal settled on the bottom.[&:]

shaun

As a test batch I have ran 15/18 and it did run better in my Echo 44 blower engine than 10/10.
I was able to tune it and get a good idle and good transition.

If there is any improvement with 15/18 there should be lots of improvement with 15/10.
At least you would know if your heading in the right direction.


I believe I'm loosing front crank bearing in it so I don't run it any more.
But I have parts on the way.

Ya know Shaun.... that's just weird.

In the states they mix ethonal in the gas.

We even have stuff that is 85% ethonal and 15% gas.

I'm trying to use a Walbro WT-644 carb for my GMS 120 glow to gas conversion. The primer bulb is on the way of prop washer. Is it possible to remover the primer bulb from the carb, and if yes beside unscrew and remove it, anything else needs to be done?

Thanks
Borna

Yea, I need to check my bearings also. I noticed a little play at the end of the spinner. (about .020" movement at 5 and 3/4 inches out from the crankcase). At first I thought it was due to the crank bearings being in a hard rubber mount, but now I'm not so sure. Where did you order your bearings from?

A lot of the Walbro carbs come either way; with the primer for an installation that needs it, and without it for an installation that has a remote primer. You could remove it, but you would need the other type fuel pump cover to replace it. If it is only the bulb itself that is in the way, and not the whole primer assembly, you might be able to make a gasket or block off plate of some sort to get rid of just the bulb itself.

AV8TOR

Shaun! maybe your gasoline is contaminated with "WATER" if it is it will settle at the bottom it happened to me once changed gasoline station and never had any problems since then.

Some numbers from running Poulan 25 with MA Classic 16x8 on 1:5 fuel (15/18 glow : 91oct Chevron gas) with glow battery power. The compression of that engine is not like my other gassers so flipping the prop is just PITA. And you never know if it starts backward so I used starter.

After I tuned the engine I got 7500 rpm top, 1500 rpm reliable iddle with OK transition. Looks like the engine is breaking in because I get better numbers every run. Now the best part. It took 15 minutes WOT (7500 rpm) to drain 8 oz fuel tank. I'm planning to put it on coroplast Piper Cub (86 inches span), with 24 oz fuel tank - it looks like I will need very big battery, because it is a lot of fuel for that engine

Now this F@#$%^ muffler is killing me. I welded these stupid pipees quite solid, but one broke loose again just after 10 minutes of running. I'm getting pissed. I hate that muffler.[:@]

Rysium: Try setting a muffler up like the ones held on by strong springs. May just work!!!! Capt,n P.S. I have seem them work on snowmobile and cycle engines.

Type in www,vxb.com. That will open thier home page. In thier search block type in 6201, i just ordered 10ea 6201rs besrings good up to 15,000 rpm. You can pop out the rubber seals or leave one side sealed. The cost was $20.90 including shipping.

I don't undestand that. The muffler I'm talking about is the one show on the picture below. Both pipes I welded to the muffler box, but one got loose again. How can I use a spring to hold them to the box?

I want to convert GMS 1.20 (20 CC) from glow to gas ignition. What Walbro carburetor is a good fit? I have a WT-644 but the problem is the the primer bulb is in the way of the prop washer and I want to remove it.

AV8TOR explain to make a gasket or block off plate to get rid of the bulb. Still not sure what I need to do. Would you please explian again what needs to be done in a little more detail to get rid of the primer bulb.

Also what other carb without primer bulb you guys suggest for 20 CC engine?

Thanks
Borna

Do you guys find it necessary to use an after run oil like atf or marvel oil in your glow weedies, or is there enough gas to keep steel from rusting?

The gas does the job. You have to treet the engine like it is gas.. You do not want to take all the gas out of the carb like you do a glow. This will keep the carb from dryrot.

For gas/oil engines, I agree with you. For Gas/Glow, I disagree. I treat my Gas/Glow engines just like my pure glow engines; I run the engine out dry, and then inject an after run oil. (I just use auto trans fluid, Marvel is good as well.) I have Gas/Glow engines that have been run like this for well over a year, (two years?) with no carb problems. My Katana sat for a year without being started. I fired it up and it ran perfectly with no adjustments or carb service needed.

The methanol in the Gas/Glow mix attracts water, and the nitro can form acids. Neither is good for the engine when left inside during storage, just as is true when running pure glow.

AV8TOR