My First Glow Plug Engine

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Peter have a read through my build that I linked to in the second post of this thread and particularly Ramons reply about lapping on the second page and also his thread on teh racers that I link to somewhere here.

The lap is parallel and most of the lapping done from the bottom end but occasionally reversed so the liner does not get too tapered. The piston is later lapped to the liner from the bottom which also takes a fraction more out of the bottom of the liner.

The idea is that the piston can move more freely below the ports but as it rises above them and you want compression it tightens up a fraction. When running the top end will expand a little due to heat in the combustion chamber which the slight taper also counters.

J

Hi Jason,

This where I goofed.Got excited.By the time I fit the piston ,the top sleeve was not slightly tapered. Now have to make new sleeve and piston and hone again.Must get it right.
Please reconfirm."If compression is insufficient,engine won't run".
Please advise best fuel for easy starting.
 
Gus if like me yours will spend its life sitting on a shelf then the lack of a taper will not be a problem, so long as you have some compression then it should run. I would try it with what you have and if it won't run then make new. The taper is really not even measurable you should just feel that the piston is a little harder to hove at the top of the stroke maybe 0.0005" difference on dia.

As for fuel any 5% nitro RC ruel should do, the stuff I used had been sitting in my shed for over 20years so was a bit stale but still got just over 8000rpm out of it.

J
 
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Gus if like me yours will spend its life sitting on a shelf then the lack of a taper will not be a problem, so long as you have some compression then it should run. I would try it with what you have and if it won't run then make new. The taper is really not even measurable you should just feel that the piston is a little harder to hove at the top of the stroke maybe 0.0005" difference on dia.

As for fuel any 5% nitro RC ruel should do, the stuff I used had been sitting in my shed for over 20years so was a bit stale but still got just over 8000rpm out of it.

J

Thanks. Jason.Taking a short break before I jump in again.

Just open up the Outer head of an OS Engine to take a peek.
Also trying the piston as it past the port holes before reaching TDC.Monkey see.Monkey do. Will get it going.

Sat'd nite fishing for good size Red Snappers.Now preparing jigs.
Will be fun.
 
Thanks. Jason.Taking a short break before I jump in again.

Just open up the Outer head of an OS Engine to take a peek.
Also trying the piston as it past the port holes before reaching TDC.Monkey see.Monkey do. Will get it going.

Sat'd nite fishing for good size Red Snappers.Now preparing jigs.
Will be fun.

Jason
Just went out to the balcony double check. Fuel has methanol and nitromethane and castor oil.Please confirm.
Will also try out on an OS glow plug engine.
 
Jason
Just went out to the balcony double check. Fuel has methanol and nitromethane and castor oil.Please confirm.
Will also try out on an OS glow plug engine.

That's perfect fuel for glow engines Gus. The percentage of nitromethane should be marked, but it doesn't really matter if you're not going to be using this engine in a plane. My first (purchased) plane engine was run-in with no nitro at all, then switched to 15%. My second engine was run-in on 15% nitro straight away.

Castor oil can leave a bit of residue compared to synthetic, but again, it doesn't matter much if the engine isn't used much, it just may feel a bit 'gluggy' and take a bit of turning over (by hand) to free up if left for a few weeks or months.

Good luck, hope to see a video.
 
That fuel sounds fine, just run the engine for short periods at first on a rich mixture and do't let it get too hot until its had time to bed in.

J
 
Thanks for the tips. After the weekend nite fishing,I am all set to solve the mystery why it just won't start and run. Gone thru many of these incidents with huge air compressors.
 
Hi Gus, I have been quietly following and enjoying your thread from the outset. I have not commented before as you have been in the good hands of Jason but if you are experiencing starting problems with your engine perhaps I can help.

Although I have operated diesels over a longer period starting glows quickly and positively became an absolute priority whilst flying control line aerobatic models (competitively that is - just one minute to start the engine, walk to the centre, pick up the handle and take off)

Firstly, though Glow motors will start with much lower compression than Diesels a reasonable piston/liner seal is still required. The kind of engine you have made will easily run on straight fuel ie 80% methanol and 20% oil. The addition of a small amount of nitro - around 5% will improve matters slightly but there really should be no need to go beyond this. Apart from the odd high revving racing engine owned I have never felt the need to go over 5% for aerobatic motors eg OS 35S , Super tigre G21/46 etc.

Assuming you are starting by hand the prop should be around 12 - 13 inch diameter for the first runs preferably with a fine pitch - 4-5". Too small a prop will mean much harder flicking required.

Technique - Fuel the tank and, if you are right handed have the prop at 'ten past eight' position as the engine comes on to compression or 'ten to four' if left handed.
Without the plug connected place a finger over the choke and turn the prop over to draw the fuel through to the carb. Prime the engine by squirting a small amount of neat fuel into the carb and flick the engine over to get the engine 'wet'. This is a 'feel' thing which you will soon become aware of. Connect up the plug and grasping the prop blade very firmly in your hand slowly bring it up to compression. If everything is right in there you will feel a positive knock on the prop as the fuel ignites against the piston - Don't worry it will not fire and start but this is an excellent indicator that it is about too. Back the prop off a little then give it a real good flick over compression when it should fire quite readily.

If you can't get a 'knock' it will mean one of two/three things -
1 There is not enough fuel through the engine ie it's not wet enough - repeat the procedure with a little more prime

2 It's too wet and you have flooded it. Disconnect the plug and close the needle and flick it over to expel the residual fuel.

3? Well check your battery and the plug! - the glow needs to be a nice bright orange at the minimum (sometimes not quite achievable with single cell nicad battery starters - some plugs are 2volt and others 1.5 which can restrict the glow on a nicad if the former) and should be visible through the exhaust port reflecting on the piston/liner wall. A small ammeter in circuit, though not essential, gives a good indication of plug condition in operation and will soon tell you if you have flooded it.


If you are using an electric starter I'm afraid I'm not much help - I have never ever used one in all my time messing with these wonderful little power houses. Just be careful you don't take the engine into a flooded situation and keep on with the starter. You could easily damage your work particularly the con rod

Hope this helps some. Congratulatons on your build, you have made a fine job of it. I hope it starts and runs as well as it looks.

Regards - Ramon
 
Hi Ramon,
Thanks for the expert advice.
The last engine I started was 55 years ago.
Doing some reverse engineering. Now trying to get a genuine bought off OS 10LA Glow Plug Engine started. The problem is Gus.Now reading your instructions plus OS instructions.Charging
the glow plug battery. Will keep you posted.

Thanks again.This forum is very helpful.
 
That fuel sounds fine, just run the engine for short periods at first on a rich mixture and do't let it get too hot until its had time to bed in.

J
wrong about the heat all nitro engines need heat cycling to get the metals up to there working tempreture range they will be running at for the life of it if its going in a model.

the rich mix is right as nitro has a cooling efect with combustion temps also the more nitro you run the better they behave etc igniton more reliable at lower rpm. so you can leave it unning as long as you like after all you have a prop mounted on it for running. make it 4 stroke on rich needle.
 
Hi Jason & Ramon

Got it. Got the bought out OS Max 10LA Glow Plug Engine started and running.This time tried not to be a smart guy.Read and comprehend OS instructions alphabet by alphabet & word by word.
Tonite will practice starting again.
Suspect I have crankcase air leak.My DIY engine did not prime well compare with OS Engine.

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Suspect I have crankcase air leak.My DIY engine did not prime well compare with OS Engine.

Some suggestions (these are more related to erratic running but might be something to check if you are not having good fuel draw).

- check for air leak bypass between carb body throat & crankcase hole. You will notice most all commercial RC glow engines have some sort of seal, usually a silicone O-ring & tight fit.

- general rule is center of fuel tank level should be about center of carb venturi port. If tank is too low, you require greater venturi suction to lift hydrostatic head of fuel. So if it starts on prime & then leans out & sputters, that could be why.

- assume you have pressure nipple of muffler attached to 2nd (air) tank line & everything unplugged/unobstructed. This line gives slight pressure oost to tank & assists fuel delivery to carb.

- check any air bypass in needle valve assembly. If you (mouth) blow into fuel line with needle valve fully open it should make a small hiss coming out the venturi hole. Many commercial engines use a nylon packer or little o-ring to ensure no air bleeds into fuel delivery & needle valve stays put under runing conditions.

Good luck!
 
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wrong about the heat all nitro engines need heat cycling to get the metals up to there working tempreture range they will be running at for the life of it if its going in a model.

the rich mix is right as nitro has a cooling efect with combustion temps also the more nitro you run the better they behave etc igniton more reliable at lower rpm. so you can leave it unning as long as you like after all you have a prop mounted on it for running. make it 4 stroke on rich needle.

These are the words from my Guru which I am following, I'm sure he will not mind me repeating them here, also remember these are not ball raced engines and don't have rings so the metal to metal needs bedding in.

"I would say the 7" pitch is a bit coarse for initial bench run's - it's always better to lightly load an engine - 4 or 5" pitch - keeping the revs up on a rich-ish mixture (for the cast in steel piston liner set up) but not allowing the head to get too hot - just about bearable with the bare fingers."

"When I began with these things so many years ago it was the norm to fit a relatively large (diameter) prop and run them slobberingly rich to run them in. It was much later that the method of lighter loads, run fairly fast on a slightly rich setting, and, most importantly, not allowing things to get hot became the accepted method. Short runs of 2-3mins gradually increasing the duration but allowing the engine to cool between runs is preferable too. As the running in progresses the needle setting can be slowly decreased letting the revs increase gradually run to run."

"On the bench there's only the prop-wash to keep things cool unlike in the air"

J
 
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Hi Jason,Ramon.
Started/Ran OS 10LA engine three more times and making observations to monkey see/monkey.
Now have all the confidence to rework and start/run my DIY engine.Suspect leaky crankcase cover and the cylinder barrel .Compression seems OK by feeling.

As a young 18 year old kid,it was amazing how I managed to get a compression engine hand started and flew.Took two weeks of sheer determination.Nodel Electric starter was not yet invented in 1960.
Now as a 69 year old man,I used electric starter to start run OS engine.

From here hopefully,Gus will look forward to build more I.C. Engines. After this engine,please advise next engine to build for collection.May build one more of same engine to practice and aquire skills and the patience.
 
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Gus, there is a diesel version of the Firefly on you-tube that uses most of the same parts you could do that as a second project, maybe Ramon could suggest details of the contra piston and other mods that would be needed.

J

PS I used an electric starter on mine too, its what I'm used to having run 1/8th scale off road and helicopters.

J
 
Gus, you are a legend! I just love your posts. Keep up the good work.

Jim
 
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Gus, you are a legend! I just love your posts. Keep up the good work.

Jim

Thanks Jim for the appreciation and encouragement.

Honestly,after giving my last part time job(7years) as Tech Consultant to a Chinese Compressor Plant,I had to find something to pass my idle time,if not Gus will rot away physically/mentally.Over the last 20 months I went into three projects which demanded patience more than skills and time.
I thought the mini tractor was easy as the magazine says followed by a steam engine which I fell in love ----must build and last this Glow Plug Engine.

When I arrived in China,they were struggling to build 5 compresors per day.When I left they were building 60 PET Compressors per day. As of mid 2011 they stop listening and past quality problems came back.Time for Gus to go.Incidently the ex-boss called and wants Gus back in China.Ha Ha Ha.

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Just been reading on Model Engine News that Alex Whitaker has a new design that he is working on so maybe you could try that Gus?

http://modelenginenews.org/ed.2012.09.html

J

Jason,

Good Idea. Will keep me busy. This time Gus will take his time,no rush,no date line but as usual as completion gets near I get over-excited and problems comes in.

Will do some minor rework to enable Firefly start/run and go on build another
to polish my skill.
 
Did minor reworks to eliminate leaks.Fuel delivery to carb improved but not as good as the OS 10LA.
Spun engine, was about to get engine started and running,handheld electric starter packed shop.Came back with new starter.Now bad to worse.Crankshaft/bush leaking oil badly.Fuel delivery compromised.

Too many fixes bad for Gus and Engine.
Decided to take a month break.Go Melbourne visit my grandchildren in Glenhuntly.Eat some good Sydney oysters.Go "Vlado for a juicy steak.Enjoy walking around Victoria Market and picking up the 2pm bargains.

Engine now a show piece on my computer desk.
Will build new engine ,all over again.This time seriously take Alex Whittaker's good advice on the "Key Fits" on the essential items.

The next Thread will titled "My Second Glow Plug Engine.
Thanks for support,encouragement and expert advice.
Its been a good two months' work.

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