Attempting Gordon Nano

[creast]

Well, the engine is complete but alas no sounds of life at all :-(
I tried flicking, RKlopps method with a rubber tube on the spinner which is much easier but still not a pop.
I even resorted to using a starter but coupled with rubber tubing which slips if hydraulic lock occurs. This gave a slight crackle at speed but nothing substantial.
The fuel I have is way old but stored in a good sealed container but I wanted to eliminate the fuel so mounted the Clanford Clan on the bench and sure enough she started and ran .
I can only guess my compression is not quite up to scratch which means another piston to make as I would expect the engine to at least show some life on priming only irrespective of any other timing/carburation problems.
Compression seemed good to me for such a small motor.
So it may be while before I am back here otherwise it may be just a failure ornament!

 

[awake]

It looks good! I am confident that you will get it working!

 

[Tim1974]

Hang in there don’t give up

 

[Peter Twissell]

What fuel mix are you using?
An engine this small has a large surface area in the combustion chamber, relative to the volume of the compressed air and fuel charge.
A lot of the heat of compression is lost into the cylinder and head, making it difficult to ignite the fuel and air.
It may start more readily with more ether in the fuel, or by priming with ether ("easy start" or similar)..
Pre-heating the head may also help.

 

[creast]

What fuel mix are you using?
An engine this small has a large surface area in the combustion chamber, relative to the volume of the compressed air and fuel charge.
A lot of the heat of compression is lost into the cylinder and head, making it difficult to ignite the fuel and air.
It may start more readily with more ether in the fuel, or by priming with ether ("easy start" or similar)..
Pre-heating the head may also help.

Hi Peter,
The mix I am using is 30% Ether, 30% Castor, 38% Kerosene and 2% amyl nitrate.
I would have preferred 35% Ether mix but getting hold of it is tricky as most suppliers will only allow collection and none are near. It's also a stupid price compared to that at shows from the dealer stands.
The thing is, the Clan which is 0.26cc started ok on this mix. I know we are talking over twice the capacity but I hoped for a more encouraging response.
I tried heating the head to no avail. I also made yet another piston which was slightly tight and took some easing in but no luck, perhaps more crackles when driven by a safe starter.
I will get a can of "Easy Start" for future trials.
Thanks for your input
Rich

 

[josodl1953]

Just a thought.. did you check if there is enough crankcase pressure for scavenging? There is only a very narrow rim that takes care of the sealing between the intake hole and the crankcase.

If there is a leak ,a scratch or whatever in this rim you may lose too much pressure to push the fresh mixture upward. To check, put the piston at TDC, put a few drops of fuel in the intake and move the piston downwards.
If any bubbles appear, there is a sealing problem. If so, all is not lost. You can always enlarge the crankshaft bearing
and put a brass or bronze bush in it ( Loctite) but it will be a fiddly operation with those small dimensions.

 

[creast]

Just a thought.. did you check if there is enough crankcase pressure for scavenging? There is only a very narrow rim that takes care of the sealing between the intake hole and the crankcase.View attachment 116590
If there is a leak ,a scratch or whatever in this rim you may lose too much pressure to push the fresh mixture upward. To check, put the piston at TDC, put a few drops of fuel in the intake and move the piston downwards.
If any bubbles appear, there is a sealing problem. If so, all is not lost. You can always enlarge the crankshaft bearing
and put a brass or bronze bush in it ( Loctite) but it will be a fiddly operation with those small dimensions.

Hi, thanks for your reply.
I don't think this is a problem and I refer you to RKlopp's comments earlier about my concerns with a small gouge from the crank drilling operation and his comments about loose carburettors etc, and he has built three engines and did get them running (jealous )
This wouldn't explain the inability to fire on prime only, i.e a short brrrurrp.
Yes I would be concerned if not running from the carb but at least firing on priming should occur so I am not convinced.
I personally think it's down to the quality of fit of the piston to the cylinder which I obviously haven't mastered and I have tried allsorts.
So far I have made 2 cylinders, 4 pistons and 3 conrods and am now on piston 5 after re-lapping the cylinder to improve finish.
I am not sure if I will carry on if no_5 doesn't work!!!
I have made pistons slightly tight before and just worked them in the cylinder with oil to bed them in but no luck.
It does worry me in using this method in just how long the engines would work anyway as they seem to bed in really quickly.
Any guidance is always welcomed.
Regards
Rich

 

[minh-thanh]

When the piston goes to TDC, does the engine keep compressing for a few seconds? (If the piston and cylinder are a little tight at TDC, you push the propeller slightly, it will return to BDC)
A really small and nice engine , Hope you make it run !

 

[creast]

Just a quick update.
Thanks to all with their encouragement and helpful hints. I am still progressing with the re-lapped cylinder and new piston but after installing the con-rod and actually achieving a press fit of the wrist pin I found the piston still needed a little lapping and I inadvertently over stressed the little end so now it's back making another rod!
In reply to minh-thanh, the compression previously seemed OK to me but at this scale it is very difficult to judge but it did bounce back and also made a nice compression plopping noise on flicking.
Another note, I couldn't get true 'Easy Start' so tried "Holts Cold Start".
For reference... don't bother with this stuff as it doesn't work even though it does smell of Ether and so raised my hopes.
I tried it on my DC Spitfire engine, which is a pig to start, as a confirmation test and no luck at all but my normal fuel worked fine.
Maybe will try to get the better stuff or, if lucky, some pure Ether ( which I doubt).

 

[sniffipn]

250ml-Diethyl-Ether

 

[Peter Twissell]

£40!

 

[creast]

£40!

My thoughts exactly!
Southern Modelcraft do 500ml for £7 Southern Modelcraft
I am hoping a show comes up this year to be able to get either high ether fuel or the Ether itself.

 

[KenC]

I am not convinced that piston seal is your problem. I too built the 0.24cc Clan and the piston fit is so soft that I can turn it over and the piston just stays at top dead centre. Despite the poor piston seal it starts easily and turns a 5x3 at 10000rpm. The things that occur to me are to look for crankcase leaks, and to check the carb and fuel system dimensions. When you block the carb and flick the prop, does the engine suck fuel along the fuel tube. And finally these very little engines love ether and will happily run on a mixture of just ether and oil, so get some ether and give a 50/50 mixture a go. And finally finally, you did drill the intake hole in the crankshaft in the correct orientation didn't you? To check just try to start the engine backwards. Don't ask how I know, but I did have to make a second (correct) crank for my Suzor "Etheromaine" diesel. If your Nano runs backwards, you will know why.
Good luck
Ken

 

[creast]

I am not convinced that piston seal is your problem. I too built the 0.24cc Clan and the piston fit is so soft that I can turn it over and the piston just stays at top dead centre. Despite the poor piston seal it starts easily and turns a 5x3 at 10000rpm. The things that occur to me are to look for crankcase leaks, and to check the carb and fuel system dimensions. When you block the carb and flick the prop, does the engine suck fuel along the fuel tube. And finally these very little engines love ether and will happily run on a mixture of just ether and oil, so get some ether and give a 50/50 mixture a go. And finally finally, you did drill the intake hole in the crankshaft in the correct orientation didn't you? To check just try to start the engine backwards. Don't ask how I know, but I did have to make a second (correct) crank for my Suzor "Etheromaine" diesel. If your Nano runs backwards, you will know why.
Good luck
Ken

Thanks Ken,
I will double check everything as advised.
The Nano doesn't seem to be as easy to coax as the "Clan" that's for sure.
Rich

 

[KenC]

Don't tempt me! After building an own-design 0.15cc diesel and then a Weaver scaled down to 0.125cc I swore I would never again build any more really tiny diesel engines. So 18 years later I built a 0.24cc Clan! If I wait a other 18 years to build a Nano I will by then be 98 and I doubt it will be high priority! Picture of 0.125cc Weevil [scaled down 1cc Weaver].
Ken

 

[creast]

Don't tempt me! After building an own-design 0.15cc diesel and then a Weaver scaled down to 0.125cc I swore I would never again build any more really tiny diesel engines. So 18 years later I built a 0.24cc Clan! If I wait a other 18 years to build a Nano I will by then be 98 and I doubt it will be high priority! Picture of 0.125cc Weevil [scaled down 1cc Weaver].
Ken

Hi Ken,
Well, I swear for starting this too. I am getting a bit bored with unsuccessful results so far but I will stick at it a while yet!
You obviously have great experience on small engines, any guidance would be gratefully received.
The Weevil looks cute, very similar to the Clan in format
Cheers
Rich

 

[Mechanicboy]

Too little ether for a tiny model diesel engine. Use this formula with high ether as here..
Kerosene - 27.5%, Ether - 40%, Castor Oil - 30%, Dope - 2.5%.

0,1 ccm is not easy to keep tight in compression, The important things to achieve when using this combination is that the bore should be tapered, wider below the exhaust ports. As a rule of thumb, the taper should be in the order of 0.0015" to 0.002" per inch of working stroke, but it's not that critical. In actual fact, it's hard to produce a fully parallel bore! So this set-up is ideal for beginners. Read this further Cylinder/piston Material Selection for Model Engines and the other about cylinder lapping How To Make and Use Cylinder Hones

 

[Mechanicboy]

Hi, thanks for your reply.
I don't think this is a problem and I refer you to RKlopp's comments earlier about my concerns with a small gouge from the crank drilling operation and his comments about loose carburettors etc, and he has built three engines and did get them running (jealous )
This wouldn't explain the inability to fire on prime only, i.e a short brrrurrp.
Yes I would be concerned if not running from the carb but at least firing on priming should occur so I am not convinced.
I personally think it's down to the quality of fit of the piston to the cylinder which I obviously haven't mastered and I have tried allsorts.
So far I have made 2 cylinders, 4 pistons and 3 conrods and am now on piston 5 after re-lapping the cylinder to improve finish.
I am not sure if I will carry on if no_5 doesn't work!!!
I have made pistons slightly tight before and just worked them in the cylinder with oil to bed them in but no luck.
It does worry me in using this method in just how long the engines would work anyway as they seem to bed in really quickly.
Any guidance is always welcomed.
Regards
Rich

Without contrapiston, you can hear the pressure from crankcase with a sound as "poow" or you can see the fog of fuel out of cylinder. If there is not pressure in crancase, make it tight between crankshaft and crankcase with a new bearing sleeve of bronce into the crankcase, but rotate free.

 

[rklopp]

Creast
You might want to take a look at the carburetor throat area. I built two of my three Nanos according to Gordon's plans for the spraybar and venturi, except I forget whether I modified the length of the portion that threads mostly across the throat. I built one with a more conventional spraybar and needle that extends all the way across the throat and out the other side. All three engines have run. On the one with the full-length spraybar, the carburetor bore is 0.094, with is per Gordon's plans, whereas the spraybar is 0.070" diameter. I have the spraybar hole aimed at the narrowest part of the passage, that is, perpendicular to the throat bore.

I recall struggling like you are to get the engines to run, and found I had better control over the venturi throat area using a full-length spraybar.

 

[creast]

Creast
You might want to take a look at the carburetor throat area. I built two of my three Nanos according to Gordon's plans for the spraybar and venturi, except I forget whether I modified the length of the portion that threads mostly across the throat. I built one with a more conventional spraybar and needle that extends all the way across the throat and out the other side. All three engines have run. On the one with the full-length spraybar, the carburetor bore is 0.094, with is per Gordon's plans, whereas the spraybar is 0.070" diameter. I have the spraybar hole aimed at the narrowest part of the passage, that is, perpendicular to the throat bore.

I recall struggling like you are to get the engines to run, and found I had better control over the venturi throat area using a full-length spraybar.

View attachment 116702

Thanks for that. I am suspicious of my jet to needle alignment plus I also made the screw slightly short so I was going to re-make the parts.
Perhaps I will try the conventional spraybar solution you suggest.
Can you tell me if you used high Ether percentage fuel?
If I really need that then its going to be a wait to get some or pay over top for some to try. Currently 35% Ether fuel available by post is £15 / litre but it's £11 courier charge!