Gas to Glow Conversion; How to do it ?

[NikolayTT]

Hi Fellows,

I have couple air blowers of 28cc, McGulloch, and on APC 18x6 they give me
about 6300 rpm. I am hoping that the conversion to Glow would help me getting
the rpm at least to 9,000. Where I can read about How to do that in details,
or at least if someone can tell me please how to replace the Spark Plug with
a Glow Plug, i.e. Where to buy from the insert which I need to screw into the cilinder head where to place the glow plug ?

Best Regards,
Nikolay
<--lame post

[3D_Kid]

Glow plug threads are 1/4-32 i believe, if you need some type of spark plug to glow plug adapter, try a local machine shop, as i don't think they make these adapters for RC makert.

[wizard]

This place should have what you need. http://wackerengines.com/ It is one of those places that can probably make it if they don't have it.

[3D_Kid]

GLOW PLUG ADAPTER
This is great for experimenters, comes with a gasket, and glow plug adapter The engine can be reconverted back to the flywheel version within minutes.

The glow plug adapter is - $18

( http://wackerengines.com/Other.htm scroll to bottom)

[tmac48]

NikolayTT, Hi I have been down this path and I can tell you that you do not want to do it. For a start you will need to work your carby ( you need to open all jetting) and you will need to dissmantle the carby after every day of flying because the methanol is very corrosive on alloy. If you still want to experiment then let me know, I may have glow adapter in the shed that you can have, I will need to know the spark plug thread size.
Regards TMAC 48

[NikolayTT]

Thank you Gentlemen for the www-pages and the advices !
The attraction in this conversion is not only the power mentioned already, it is also
as you know, the lighter weight of the engine without the Ignition wheel and Magnet. Walbro carburator is having good membrane pump but beside the dificulties of drilling the jetts now I learned from tmac48 about the methanol being agressive to the alloy and that problem is really nasty. I should plan then to look for a very simple Carburator from second hand broken glow engine from eBay for example and try to adapt it. Thanks for warning me ! About the glow plug adapter: - I will really appreciate if I can have a least a look how the one tmac48 has; could you E-mail a photo ? Also please let me know what would be the cost to have that adapter from you ? As for the the spark plug thread size is a bit of mistery for me at this moment; I will find out and E-mail. Still, the glow plug offered by wackerengines.com is a solution but it looks it is placed quite high above the head, i.e. looks to me a bit too far from the combustion chamber. I red that those Gas engines have lower compression ratio than the needed one for the efficient work of Glow ones. I am not sure but if that is the case, then with that adapter the things are going in oposite direction, isn't it ? Anyway, then a MAJOR QUESTION still remains: - How big is the gain of this not easy exercise, do I really get any improvements in the performance
or I will just have the problems and the only gain is the decreased weight
from the not needed ignition system ? i.e. what the Tachometer of tmac48
"tells" when such engine was converted to glow, any visible power gain ?
Regards,
Nikolay

[3D_Kid]

no problem man, good luck

[XJet]

	Quote: Originally Posted by tmac48
	NikolayTT, Hi I have been down this path and I can tell you that you do not want to do it. For a start you will need to work your carby ( you need to open all jetting) and you will need to dissmantle the carby after every day of flying because the methanol is very corrosive on alloy.

But aint it funny that *every* glow-plug model engine I know of uses an aluminum crankcase, aluminum carburetor and an aluminum head.

I wonder why they're not all falling apart? :-)

But you are right, *some* aluminum alloys react badly to methanol, but not all of them. I suspect that the alloy used for carb-bodies is often a relatively low-grade alloy which is susceptible but I would imagine that the high silicon content in the castings of most glow-engines is far more resistant to this.

[tmac48]

NikolayTT. I will post photos of plug adapter for you. The glow plug element on this adapter is set deep so as to be in the same flame front as the original spark plug,it is level with the bottom of the threaded adapter (hope that makes sense)

Please be aware that if you put a gas engine on glow that you now have an engine that has an awful lot of advanced ignition and you can not hand flick the prop as you once did.To stop the prop from kicking back on you I would place the flat of my fingers on the flat of the prop and wipe it against compression in a clockwise direction,it will bounce back in the anticlock direction and continue to run.
The motor that I put on glow was a WEBRA BULLY (20 YRS AGO) and I found that it was a better motor when I used a CH ignition with advance and retard(in those days this was a mechanical set up straight from the carby throtle linkange)
Mate, do yourself a faver and dont go down this road, another problem you have is that HEAVEY MAG and fly wheel that you want to get to get rid of,well that is a counter weight to help balance the engine. Having said all this if you want to experiment then I wish you well and I will send plug adapter no charge as long as you post your progress and findings.
Regards TMAC48.

[tmac48]

	Quote: Originally Posted by XJet
	But aint it funny that *every* glow-plug model engine I know of uses an aluminum crankcase, aluminum carburetor and an aluminum head. I wonder why they're not all falling apart? :-) But you are right, *some* aluminum alloys react badly to methanol, but not all of them. I suspect that the alloy used for carb-bodies is often a relatively low-grade alloy which is susceptible but I would imagine that the high silicon content in the castings of most glow-engines is far more resistant to this.

Yes, try putting methanol in your chain saw and see what it does to the alloy fuel tank, dont ask me how I know this!

[wizard]

	Quote: Originally Posted by tmac48
	Please be aware that if you put a gas engine on glow that you now have an engine that has an awful lot of advanced ignition and you can not hand flick the prop as you once did.To stop the prop from kicking back on you I would place the flat of my fingers on the flat of the prop and wipe it against compression in a clockwise direction,it will bounce back in the anticlock direction and continue to run.

I will second the fact that the conversions are hard to start. I have one engine that is a gas to glow conversion. I received it as part of a trade. It was converted by a company that is no longer in business. The only markings on it are "Rhino 1.40" put on with an engraver.

I have fought this engine many times. With the size of the engine, neither starter I have will spin it, so the only option is to hand prop it. It is very bad about wanting to run backward. With the one I have, trying the trick of spinning it backward doesn't work. It will just start backward. To get mine to start the mixture has to be just right. If the mixture is too rich, it will kick back and run backward every time.

I am thinking of replacing this engine with a gasser this year. Just to make life a lot simpler.

[NikolayTT]

Hi,

Thanks a lot for the offer to tmac48 ! Yes, I will post the results as soon as
the weather here (Finland!) permits me to go outside and start the engine.
Right now it is just about -7 deg Centigrade and althoug I been flying my
methanol planes till up to -16deg.C it is not really much pleasure and the
gas to methanol conversion will need more "relaxing" temperature. My address
for the posting is:
Nikolay T. Tchamov
Tampere Univ.Techn.
Korkeakoulunk.1, TH-108
33720 Tampere
Finland

As for the reverse starting of the engine I avoide that by using the starter
always; I use the ultra torque from Tower Hobbies and it works fine with
compression of engines up to 40cc types.

It is in fact interesting: - Can't we make some good use of the reverse
rotation of the engine, meaning, has been there someone to measure the
power of this way of rotating and then use it for a Push-Prop set-up, if
there is good power and stable run? Sometimes it is more difficult to
find reversed propellers, and in fact some engine makers offer of
Reverse Crank-shafts for Push-Props which are "almost the same" as
those for Normal rotation and one can use regular prop.

Best Regards,
Nikolay