# Glow engine



## minh-thanh (Jul 19, 2018)

I'm starting the glow engine 
I have a question, With a beginner: Should do engine with contra piston  or with Glow plug hot ??
Thanks !


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## lohring (Jul 19, 2018)

Glow plug engines are a lot easier to operate.  Their fuel is also easier to get and/or mix.  I would start with a proven, simple design.

Lohring Miller


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## WOB (Jul 19, 2018)

For a beginner, you have a much better chance of success with a glow-plug.    Diesels require a very good piston to cylinder fit that can only be achieved by lapping.   The process is exacting and time consuming, requiring tools that most beginners don't have in their shops.  See this page to get an idea of what's required: http://adriansmodelaeroengines.com/catalog/main.php?cat_id=178

WOB


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## minh-thanh (Jul 19, 2018)

Thanks Lohring Miller , WOB !
And WOB ,  thank you for sharing, i learned something in this link.


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## lohring (Jul 20, 2018)

Do you have a design in mind?  Two strokes can be very simple and still perform well.  

Lohring Miller


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## minh-thanh (Jul 20, 2018)

lohring said:


> Do you have a design in mind?  Two strokes can be very simple and still perform well.
> 
> Lohring Miller


Thanks for your question.
Yes , i have a design in mind . 
I will do the plan in this thread
https://www.homemodelenginemachinist.com/threads/mp-3-2cc-glow-engine.26858/#post-294448
But I will change some details to fit the way I do it.


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## lohring (Jul 20, 2018)

That's an excellent beginners design that should have reasonable power.  The iron piston in a steel sleeve works very well when built as described.  If you want to run it in a radio controlled vehicle, there are standard carburetors that can be substituted for the intake with minor modifications.  By the way, glow plugs use a 1/4-32 tap.  That should be easy to get on line.  If not, I have extras

Lohring Miller


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## minh-thanh (Jul 20, 2018)

Lohring Miller !
 ""  there are standard carburetors that can be substituted for the intake with minor modifications."" : I'm learning about how it works.
"" If not, I have extras "" If you talk about those plans of engine, that's great !!


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## lohring (Jul 21, 2018)

A carburetor like this from ASP should work well.  Do you need a 1/4-32 tap?

Lohring Miller


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## Keith whiddett (Jul 21, 2018)

Hi I am considering building this engine, is it possible to move the hole for the Venturi towards the front about 4 mm to make room for a throttle carburettor? I am asking because I was thinking it might weaken the crankshaft so the transfer hole would be that much longer. Many thanks for the design,I will post here when finished but that might be a few months


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## lohring (Jul 22, 2018)

I would angle the carb forward and try to keep the crankcase hole in the same position.

Lohring Miller


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## kf2qd (Jul 22, 2018)

Don't go to small on your first one. A slightly larger engine is a bit more tolerant on tolerances. You might take a look at the .60 size 2 stroke that I loaded to the download section a few years back. 

Okay, now that I look around, where did the downloads go??? Or is it me???

If you would like a copy I can email you one. DWG or PDF?


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## Cogsy (Jul 23, 2018)

kf2qd said:


> Don't go to small on your first one. A slightly larger engine is a bit more tolerant on tolerances. You might take a look at the .60 size 2 stroke that I loaded to the download section a few years back.
> 
> Okay, now that I look around, where did the downloads go??? Or is it me???



The downloads are now threads found under the 'Engines and Downloads' section of the forum - LINK. I did a quick search for your uploads and this is what shows up - LINK.


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## minh-thanh (Jul 23, 2018)

Hi lohring  !
I have answered you, but it goes away - maybe I forgot to send! I'm sorry
With 1 / 4-32 tap: I bought it
With link for carburetor: I will buy it when the engine runs

Hi kf2qd ! All information is good for me. If you can, send me the link or copy  DWG and PDF , or one file PDF . 
Thanks


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## Keith whiddett (Jul 23, 2018)

kf2qd said:


> Don't go to small on your first one. A slightly larger engine is a bit more tolerant on tolerances. You might take a look at the .60 size 2 stroke that I loaded to the download section a few years back.
> 
> Okay, now that I look around, where did the downloads go??? Or is it me???
> 
> If you would like a copy I can email you one. DWG or PDF?


If you could send p d f on the 10cc engine would be great. [email protected]


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## Keith whiddett (Jul 23, 2018)

If you could send p d f on 10cc engine would be great to [email protected]. Many thanks


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## minh-thanh (Jul 24, 2018)

.. nothing ...
I decided with the plan : https://www.homemodelenginemachinist.com/threads/mp-3-2cc-glow-engine.26858/#post-294448
With some modify


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## WOB (Jul 24, 2018)

Keith whiddett said:


> If you could send p d f on 10cc engine would be great to [email protected]. Many thanks



Keith you might like this one:  http://modelenginenews.altervista.org/mecd/3584.img.html#521
Castings are available at    http://www.hemingwaykits.com/acatalog/Jones_605___Colin_Jones.html

I built it a few years ago, and it is a screamer.  Powerful and loud.

WOB


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## Keith whiddett (Jul 24, 2018)

Have made a start, bucket full of swarf later!!!


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## Keith whiddett (Jul 24, 2018)

WOB said:


> Keith you might like this one:  http://modelenginenews.altervista.org/mecd/3584.img.html#521
> Castings are available at    http://www.hemingwaykits.com/acatalog/Jones_605___Colin_Jones.html
> 
> I built it a few years ago, and it is a screamer.  Powerful and loud.
> ...


Hi thanks for the info, perhaps my next engine


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## minh-thanh (Jul 24, 2018)

The same plan with me


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## minh-thanh (Jul 25, 2018)

some modify : ( maybe good or not, i don't know...just thinking and doing, If wrong, I will add experience for myself )


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## minh-thanh (Jul 27, 2018)

Hi all !
I have two questions:
- Can i use 4-stroke engine fuel regulator for it ?
- Fuel: How much nitro ?
Thanks.


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## Keith whiddett (Jul 27, 2018)

You will need two stoke model engine fuel which is methanol and oil!!! 75%methnol 25 %castor oil it will run on this but 5 % nitro will help it run better. And a good 2volt battery for the glow plug. Good luck. lol forward to the video of it running


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## minh-thanh (Jul 27, 2018)

Thanks Keith whiddett !


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## Keith whiddett (Jul 27, 2018)

Meant to add you can use the same carberretta for two or four stroke


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## minh-thanh (Jul 27, 2018)

I test run it, it's not running, i will unfix it and check it again, i'm wrong somewhere...


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## kadora (Jul 28, 2018)

Try to inject /syringe with needle/ small amount of fuel straight into cylinder trough exhaust port.
This overflow sometime helps to start engine.


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## ixb1 (Jul 28, 2018)

Hi guys, its pleasant to see that my boy have more brothers around the globe.


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## minh-thanh (Jul 28, 2018)

kadora said:


> Try to inject /syringe with needle/ small amount of fuel straight into cylinder trough exhaust port.
> This overflow sometime helps to start engine.


Thanks kadora ! 
It 's not run .


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## ixb1 (Jul 28, 2018)

Not runnig?!
If you remove plug and turn shaft,move its freely?
If you put plug into head and flip prop counter clockwise,did you feel resistance by compressed air and hear popping sound?
Filament in glow plug glowing if connected to baterry?


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## minh-thanh (Jul 28, 2018)

Hi ixb1 ! 
 remove plug and turn shaft,move its freely : yes 
put plug into head and flip prop counter clockwise,did you feel resistance by compressed air and hear popping sound : yes
Filament in glow plug glowing if connected to baterry : yes 
I think i make the clearance between the crankshaft and the font bearing to much


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## ixb1 (Jul 28, 2018)

If you put about 1/2 ml of fuel into intake valve and flip prop few times,fuel will drain from front bearing?


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## minh-thanh (Jul 28, 2018)

Yes ! fuel  drain from front bearing.


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## ixb1 (Jul 28, 2018)

How big is shaft clearance in bearing?


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## minh-thanh (Jul 28, 2018)

ixb1 !
shaft clearance in bearing : 0.3 mm .


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## ixb1 (Jul 29, 2018)

Hmm this is too much.


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## Mechanicboy (Jul 29, 2018)

Clearance of crankshaft is too much.. you need this book, see chapter two about fits and tolerances in page number 17  (part A). 
The tolerance in crankshaft/bearing in front house must be very little clearance and running without friction when the engine is new. Use the adjustable reamer to adjust the diameter in the bearing and try each time until the crankshaft goes into bearing without slack. 

Download this book part A and B, print out and create a book, worth to have in your workshop. 
https://rclibrary.co.uk/files_titles/1996/Engine_Encyclopedia_RonMoulton_partA.pdf
https://rclibrary.co.uk/files_titles/1996/Engine_Encyclopedia_RonMoulton_partB.pdf

Picture of the set of adjustable reamer..


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## Mechanicboy (Jul 29, 2018)

Front house bearing - 10 mm H7 = +0,000 - +0,015 = 10,000 mm - 10,015 mm
Crank shaft - 10 mm g6 = -0,005 - -0,014 = 9,995 mm - 9,986 mm

I prefer to make crankshaft first 10,000 mm when the shaft is polished with fine emery paper #500-800 or lapping ring + lapping paste for shaft if you want (+ or - not so very important in tolerance since the lathe is never 100% precision). Measure 10 mm diameter must be same in whole length of crank shaft, use emery paper if one of the part of crank shaft is too thick (must be parallel in length).  Then drill the bearing house with 9,8 mm  drill and use reamer to adjust the diameter, then ream into the bearing house and try each time with crank shaft until the crank shaft fit into the bearing without slack and rotate free with oil applied on..


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## minh-thanh (Jul 29, 2018)

ixb1 said:


> Hmm this is too much.


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## minh-thanh (Jul 29, 2018)

Thanks Mechanicboy !
I'm doing it again. Maybe it would be better...


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## ixb1 (Jul 29, 2018)

Very interesting book ,thanks for sharing.


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## Mechanicboy (Jul 29, 2018)

I has the book i bought a lot of year since.. then i build the first glow plug engine and later model diesel engine of my own construction and from some plans. 

Common novice errors are the design of transfer ports and exhaust ports that do not work efficiently that the engine is very difficult to start up or loses a lot of power when the engine is running. I would recommend Scnuerle porting system fig. f and fig. g  (fig. g:  the boost port is lower than two other transfer port) or exhaust on both sides and transfer port front and rear fig. d which works best for first model engine builder. I have experienced it from my own mistakes when I designed transferport / exhaust ports.

And much easier if you have a reed valve in the back cover where the carburetor is mounted on back cover since timing is not critical (timing is fully automatic).  The reed valve is locked with spring lock ring same as Cox engine to example. The reed valve can be made of plastic sheet or beryllium copper sheet (difficult to buy, then i used the plastic sheet as valve, last very well).  Rotary valve in the crankshaft also works very well. If you want to make engine with reed valve, ask me then i give you a plan of back cover with reed valve.


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## ixb1 (Jul 29, 2018)

Reed valve is fairly simple to make. I make it experimentaly from 0,05mm steel and plastic foil with same result.Engine with RV have very good starting ability ,but it have one minus.It often start running in reverse direction.


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## minh-thanh (Jul 29, 2018)

Hi Mechanicboy !



Mechanicboy said:


> And much easier if you have a reed valve in the back cover where the carburetor is mounted on back cover since timing is not critical (timing is fully automatic).  The reed valve is locked with spring lock ring same as Cox engine to example. The reed valve can be made of plastic sheet or beryllium copper sheet (difficult to buy, then i used the plastic sheet as valve, last very well).  Rotary valve in the crankshaft also works very well. *If you want to make engine with reed valve, ask me then i give you a plan of back cover with reed valve*



That's Great !
Please send for me : [email protected]
Many thanks ,Mechanicboy !


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## Mechanicboy (Jul 29, 2018)

Minh Thanh, e-mail not necessary.. I'm showing the photo and drawings of reed valve. It's not difficult to create the back cover with reed valve as you see at my drawings.  The engine can run in both ways also you can use the engine as traction or pusher in the airplane to example.  



The engine was my first diesel engine, created on Unimat Emco 3.















 Crankshaft from shock damper from car. Crank case cast from old water pump for car. Piston from camshaft (cast iron), cylinder from drive shaft (high tensile steel).


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## Keith whiddett (Jul 29, 2018)

You could fit bronze front bearing, lap crank shaft to it


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## minh-thanh (Jul 29, 2018)

Mechanicboy ! 
Thank you for your pictures ! They are clear and easy to understand
Thank you very much !

Keith whiddett !
Thanks for your suggestion.

I will try to do well...


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## Keith whiddett (Jul 30, 2018)

The way the fuel is going into engine isn’t your problem. You are losing crankcase compression through the front housing. Fit bronze bush to front of housing and lap it to crankshaft don’t worry if it’s a bit tight it will bed in. Do you have electric starter? To turn engine over fast this will help. Do you have good compression? Also the porting in cylinder must be correct to the drawing.


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## minh-thanh (Jul 30, 2018)

Hi Keith whiddett !
- The way the fuel is going into engine isn’t your problem : yes . But I'm thinking: I'll try to do everything as plan (I'm not sure because it depends on what I have, the machinery, my experience .... ), if it's not running I'll follow the Mechanicboy's scheme on the reed valve, I just need to adjust the back cover with the reed valve. I need it to run, and when it runs I will understand more about it...
- You are losing crankcase compression through the front housing. Fit bronze bush to front of housing and lap it to crankshaft don’t worry if it’s a bit tight it will bed in  : That's a good suggestion.
-  Do you have electric starter? To turn engine over fast this will help : yes , i have electric starter
-  Good compression :yes , it has compression, but I don't know how to determine good or not? because it was my first engine
-  the porting in cylinder must be correct to the drawing : I will check it again.
Thank you very much !


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## Keith whiddett (Jul 30, 2018)

Remove glow plug and connect battery it should glow bright orange. I think the fuel going in to engine might be blown out though front bearing because because fit not good enough. It should go into crankcase and blown up through the ports. Be carefull with starter it can bend con rod if you get to much fuel in cylinder


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## Keith whiddett (Jul 30, 2018)

Bit more done today, all day doing crankshaft and propdriver!!!!


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## minh-thanh (Jul 30, 2018)

Hi all ! 
Can I use the this fuel for my engine ?


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## Mechanicboy (Jul 30, 2018)

minh-thanh said:


> Hi all !
> Can I use the this fuel for my engine ?
> View attachment 103124


Yes, it's this as model glowengine fuel.


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## minh-thanh (Jul 31, 2018)

Thanks Mechanicboy !
updated on my engine
Today, I made bronze bush for front house bearing
AND, it ran for 25-30 seconds, twice. 
I unfix it agian, check it ... I noticed the shaft is not good and it does not fit perfectly with the front of housing, I will do the new shaft and try to fit best with the front house bearing,. I hope it will be okay


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## Keith whiddett (Jul 31, 2018)

Thought that was the problem


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## minh-thanh (Aug 3, 2018)

Hi All !
Updated  :


Now it is very easy to run, but when i unplug  connect battery it stops. I do not understand why ??


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## kadora (Aug 3, 2018)

Your engine has very low idling RPM and glow plug filament probably cools down between ignitions.
Try four stroke glow plug.
Anyway amazing low idling on your two stroke baby - congratulation.


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## ixb1 (Aug 3, 2018)

Yes it runs well.I must say that your engine is different than i expected.
Ordinary glow engine if it stops when battery is disconnected, it is caused by too rich fuel mix or low compression ratio...But in this method of carburation i dont know.
Small two stroke also needs plenty of oil for cooling and lubrication. Literarly say oil must spray from exhaust.


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## Keith whiddett (Aug 3, 2018)

It’s two rich mixture on  idle and it’s not two stroking, you need to lean it out so it runs faster. But not for to long with A fly wheel, it needs a propeller for cooling and much lighter will run faster. Propeller size 9 x 6 or 9x4. 
Well done


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## minh-thanh (Aug 3, 2018)

kadora ! 
*Try four stroke glow plug* : I will try it .

ixb1 !
*Ordinary glow engine if it stops when battery is disconnected, it is caused by too rich fuel mix or low compression ratio...But in this method of carburation i dont know.
Small two stroke also needs plenty of oil for cooling and lubrication. Literarly say oil must spray from exhaust.*
I will check it again.

Keith whiddett
*it needs a propeller for cooling and much lighter will run faster. Propeller size 9 x 6 or 9x4 : *I will try it

Thanks ixb1 for the plan .
Thanks for all suggestions .
I will check and redo....I hope it will be better .


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## Mechanicboy (Aug 4, 2018)

There is evaporated fuel into the carburetor instead atomized fuel mix into the carburetor, but it ran!  

Use ordinary carburetor with spray bar due the engine need oil from fuel to keep compression better + 4 stroke glow plug ("F" stamped on glow plug  to example). Compression ratio must be 8:1 -9:1 to keep engine running without battery attached to glow plug and the glow plug is glowing by catalytic reaction from methanol too. 

http://adriansmodelaeroengines.com/catalog/main.php?cat_id=153


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## minh-thanh (Aug 4, 2018)

Thanks Mechanicboy !


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## Johno1958 (Aug 5, 2018)

Very nice runner Minh Thanh congratulations .
John


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## minh-thanh (Aug 5, 2018)

Hi all !
Updated and finished :
Now it runs without battery connection. It did not work well because I unfix too much, some parts were not good, but it was a learning experience for me, I learned a lot of things when doing it



Thank you very much ! Thank you all !


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## lohring (Aug 5, 2018)

Two strokes are a great introduction to engine building.  They are very simple and work even if not perfectly designed or built.  I learned most of what I know about manufacturing by building a model racing engine in high school.  It was also the start of my fascination with two stroke design. 

In small engines, friction is by far the most important factor because the power producing displacement decreases much more quickly with size than the surface area of parts like the cylinder.  Ball crankshaft bearings have become standard.  Some engines have also used needle connecting rod big end bearings. 

Sealing also becomes more critical since clearances also don't decrease as quickly as displacement.  Before careful machining was standard, ringed aluminum pistons were used in steel (sometimes hardened or chromed) cylinders.  The final solution in small engines has been lapped fits between the cylinder and piston using materials with similar rates of expansion.  In order of increased performance and difficulty these materials are cast iron on steel, high silicon aluminum on chromed brass, and high silicon aluminum on chromed high silicon aluminum. 

After these considerations, the cylinder head volume is important.  It sets the ignition timing for glow engines and needs to be matched with the plug heat range and fuel.  Racing engine tuners use head shims and machine lots of head buttons.  After all this comes the port shape and timing.  Cross flow and reverse flow engines are the easiest to build, but loop flow engines are more powerful with carefully aimed ports and a tuned pipe.  All designs can work well with open exhaust.  See the pictures below.  Tuned pipes have more than doubled the output of today's race engines over the simple engine I built long ago. 

Keep on refining your engine.  It will teach you a lot.

Lohring Miller


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## minh-thanh (Aug 6, 2018)

Thanks lohring !


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## natalefr (Aug 6, 2018)

Your engine is nice good luck


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## Keith whiddett (Sep 2, 2018)

At last it’s finnished starts and runs well, still a bit tight so running rich trying to Load video but to high res


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## Keith whiddett (Sep 2, 2018)

Video on you tube search for glow engine 3.2cc


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## ixb1 (Sep 2, 2018)

Very well Keith.


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## minh-thanh (Sep 2, 2018)

Very well ! Better than my engine


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## Keith whiddett (Sep 4, 2018)

made a new head today, thinks it looks better!!


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## Keith whiddett (Sep 10, 2018)

Now sporting a silencer!!!! Must change the 3mm bolts for mushroom heads!!


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## minh-thanh (Sep 11, 2018)

Wow !


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## minh-thanh (Sep 11, 2018)

Hi all !
I want to learn more about it and after changing the structure, but keep true - approximate - technical requirements: cylinder diameter, stroke ....


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## minh-thanh (Sep 11, 2018)

and Video :


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## Keith whiddett (Sep 12, 2018)

minh-thanh said:


> and Video :



Looks good but it running slow. Is there a reason for that, running in??


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## minh-thanh (Sep 12, 2018)

It's running slow because I'm adjust it slow  , If I adjust it too fast it will turn  the needle - because the needle is not tightened


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## lohring (Sep 13, 2018)

If you are interested, I've written a series of articles on two stroke engines.  The first series is in 4 parts on High Power Two Stroke Design:

http://namba.com/content/library/propwash/2012/November/#/14/ 
http://namba.com/content/library/propwash/2013/March/#/3/ 
http://namba.com/content/library/propwash/2013/October/#/8/ 
http://namba.com/content/library/propwash/2014/October/#/7/

The second series is just starting on the history, design , and building of model racing two strokes.  The first article is at http://namba.com/content/library/propwash/2018/october/14/ and it discusses the history of the nitro engine.  The following articles will go into the details of building high power model glow engines.

Lohring Miller


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## Keith whiddett (Sep 13, 2018)

lohring said:


> If you are interested, I've written a series of articles on two stroke engines.  The first series is in 4 parts on High Power Two Stroke Design:
> 
> http://namba.com/content/library/propwash/2012/November/#/14/
> http://namba.com/content/library/propwash/2013/March/#/3/
> ...


Wow thanks for that will check it out. 
Being a very long time aero modeller I was looking at the transfer ports on a OS61 engine and there are three of them. The middle one is  opersite the exhaust outlet, and opens well before the other two !! I guess this is to scavenge the exhaust out quicker???


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## minh-thanh (Sep 13, 2018)

Lohring Miller ! Thanks for share . 
there are many things to read..


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