3cc Diesel - My first ICE
- Thread starter Maryak
- Start date
Help Support Home Model Engine Machinist Forum:
OK .............. I'm stood on the garage roof looking South ........... how long till "Kick Off" ;D
No, I'm not really going to stand there all night :
.......... Good luck Bob ........... looking forward to tomorrows instalment ....... or for you guys is it "Today's instalment" :
CC
No, I'm not really going to stand there all night :
.......... Good luck Bob ........... looking forward to tomorrows instalment ....... or for you guys is it "Today's instalment" :CC
Maryak
Well-Known Member
- Joined
- Sep 12, 2008
- Messages
- 4,990
- Reaction score
- 77
WOOPEEEEEEEEEEE
IT RUNS
As promised and at great expense to the management
There was a fair bit of detonation in the first run so had a bit of a play with the fuel and this second run is a lot better but still a bit of tweaking.
Guys, I cannot thank you all enough for your support and encouragement. I am over the moon. :bow: :bow: :bow: :bow: :bow: :bow:
Best Regards
Bob
IT RUNS
As promised and at great expense to the management
There was a fair bit of detonation in the first run so had a bit of a play with the fuel and this second run is a lot better but still a bit of tweaking.
Guys, I cannot thank you all enough for your support and encouragement. I am over the moon. :bow: :bow: :bow: :bow: :bow: :bow:
Best Regards
Bob
- Joined
- Feb 17, 2008
- Messages
- 2,326
- Reaction score
- 440
Thats great Bob.
It not only looks good but it runs well also.
It's a great credit to you for getting your first IC engine running. Many first efforts don't run at all, but yours is fantastic. :bow: :bow:
Gail in NM,USA
It not only looks good but it runs well also.
It's a great credit to you for getting your first IC engine running. Many first efforts don't run at all, but yours is fantastic. :bow: :bow:
Gail in NM,USA
Bob she's a bottler
gret soundin too
well done mate , its been a class act all the way
i've learned a heap
and have a lot to look forward too thanks to the doco'd way you have done this
beats a plan set and instruction book any day
thanks and again
bloody well done
cheers
jack
gret soundin too
well done mate , its been a class act all the way
i've learned a heap
and have a lot to look forward too thanks to the doco'd way you have done this
beats a plan set and instruction book any day
thanks and again
bloody well done
cheers
jack
Maryak
Well-Known Member
- Joined
- Sep 12, 2008
- Messages
- 4,990
- Reaction score
- 77
Gentlemen,
Thank you so very much for your kind words, your support and your encouragement. You are all a very large and important part of my success. :bow: :bow: :bow:
There's quite a bit of missing, I think the kero is off spec, added a little petrol and it helped but not quite there yet. - Gail any suggestions ???
It's also very fuel hungry, about 10ml/min - normal ???
I am going to have to put some thread tape on the compression screw as it vibrates off its' setting, another reason for missing.
Lastly, me and my workbench, not to mention the engine covered in castor oil and ether, no wonder I,m sleepy
. Mine seems to be a very messy engine.
I am home enjoying a couple of stiff brandies and coke
Once again thanks to all.
Grins bigger than mine ??? ??? I find that hard to imagine
but thanks Rick.
Best Regards
Bob
Thank you so very much for your kind words, your support and your encouragement. You are all a very large and important part of my success. :bow: :bow: :bow:
There's quite a bit of missing, I think the kero is off spec, added a little petrol and it helped but not quite there yet. - Gail any suggestions ???
It's also very fuel hungry, about 10ml/min - normal ???
I am going to have to put some thread tape on the compression screw as it vibrates off its' setting, another reason for missing.
Lastly, me and my workbench, not to mention the engine covered in castor oil and ether, no wonder I,m sleepy
I am home enjoying a couple of stiff brandies and coke
Once again thanks to all.
Grins bigger than mine ??? ??? I find that hard to imagine
Best Regards
Bob
- Joined
- Feb 17, 2008
- Messages
- 2,326
- Reaction score
- 440
Bob,
I can only offer a couple of suggestions.
Easy one first. Compression screw.
The bottom of the compression screw should have the last bit of thread removed so none of the thread can touch the contra piston. Also, the end of the compression screw should have a recess in the center that is about 1/2 the diameter of the root diameter of the thread so you have a ring touching the contra piston. Both of these will reduce the tendency for the compression screw to wander while running. In extreme cases it may be necessary to add a lock nut of some kind. A scrap of something about 1mm thick and shaped like a keyhole with a tapped hole for the compression screw works well. A little more on this when discussing the missing.
Now the hard one. Missing and fuel consumption.
Adding petrol to compression ignition (CI) fuel is normally the wrong thing to do. Petrol has a self ignition temperature about 30 to 40 degrees higher than kerosene. Also the explosive limits of mixture are higher. The fact that it helped and your fuel consumption is a little high may be related. I would expect the consumption to be about 4 to 5 ml/min when the engine is broken in, or about half of what you are seeing. I doubt the kerosene quality is a problem. CI engines are very forgiving about the kerosene grade and most anything is fine as long as looks and smells like kero. I have never tried them, but I have been told that some of smokeless and perfumed lamp oils don't work too well because of all the additives.
Looking at all the above, I am guessing that the contra piston is too loose. Some time back I think I told you the contra piston needs to be 3 times tighter than what you think it should be. What I think is happening is that you are having to run a rich mixture to get enough oil to seal the contra piston. Adding petrol will force a richer mixture due to the higher explosive limit and increase the fuel consumption. Also a contra piston that moves at all during running will cause the compression screw to move.
An undersize piston will also cause increased fuel consumption, but it is much more forgiving as it is moving and forms a dynamic seal. It also gets a lot more fresh oil every stroke which helps it seal.
I don't think that is your problem.
You did not say if you "doped" the fuel you mixed with an ignition promoter. At the speed your engine is running, I don't think doping the fuel with a nitrate or nitrite would have any real effect, but it might smooth it out some when it is broken in and running at higher speeds. I don't think would help with the missing.
All of the above is a guess, but a guess based on building an running CI engines for quite a while.
And yes, CI engines are ALL messy.
Gail in NM,USA
I can only offer a couple of suggestions.
Easy one first. Compression screw.
The bottom of the compression screw should have the last bit of thread removed so none of the thread can touch the contra piston. Also, the end of the compression screw should have a recess in the center that is about 1/2 the diameter of the root diameter of the thread so you have a ring touching the contra piston. Both of these will reduce the tendency for the compression screw to wander while running. In extreme cases it may be necessary to add a lock nut of some kind. A scrap of something about 1mm thick and shaped like a keyhole with a tapped hole for the compression screw works well. A little more on this when discussing the missing.
Now the hard one. Missing and fuel consumption.
Adding petrol to compression ignition (CI) fuel is normally the wrong thing to do. Petrol has a self ignition temperature about 30 to 40 degrees higher than kerosene. Also the explosive limits of mixture are higher. The fact that it helped and your fuel consumption is a little high may be related. I would expect the consumption to be about 4 to 5 ml/min when the engine is broken in, or about half of what you are seeing. I doubt the kerosene quality is a problem. CI engines are very forgiving about the kerosene grade and most anything is fine as long as looks and smells like kero. I have never tried them, but I have been told that some of smokeless and perfumed lamp oils don't work too well because of all the additives.
Looking at all the above, I am guessing that the contra piston is too loose. Some time back I think I told you the contra piston needs to be 3 times tighter than what you think it should be. What I think is happening is that you are having to run a rich mixture to get enough oil to seal the contra piston. Adding petrol will force a richer mixture due to the higher explosive limit and increase the fuel consumption. Also a contra piston that moves at all during running will cause the compression screw to move.
An undersize piston will also cause increased fuel consumption, but it is much more forgiving as it is moving and forms a dynamic seal. It also gets a lot more fresh oil every stroke which helps it seal.
I don't think that is your problem.
You did not say if you "doped" the fuel you mixed with an ignition promoter. At the speed your engine is running, I don't think doping the fuel with a nitrate or nitrite would have any real effect, but it might smooth it out some when it is broken in and running at higher speeds. I don't think would help with the missing.
All of the above is a guess, but a guess based on building an running CI engines for quite a while.
And yes, CI engines are ALL messy.
Gail in NM,USA
Maryak
Well-Known Member
- Joined
- Sep 12, 2008
- Messages
- 4,990
- Reaction score
- 77
Gail,
Thanks very much for your comprehensive response to my queries.
Yes, the last 1/8" is free of thread; and no there is no recess in the bottom, (will fix that tomorrow).
Lamp oil in its natural state is in fact 300 test kerosene used in Hartridge machines for setting diesel fuel pumps and injectors. (A snippet from Bob's glossary of useless knowledge). The perfumes and dyes added by various religious orders definitely reduce its' performance as a fuel.
I hear what your saying about the contra piston. If I had to push any harder to get it into the cylinder, I would say it was a 1:1 interference fit - maybe that's whats needed ???
There is no dope in my mix, other than the dope doing the mixing :
When I remove the compression screw tomorrow I will be able to see how much fuel is under the head. There was minimal leakage around the screw and non down the sides between the head and cylinder.
It's good to know all CI engines are messy. I smelled like a cross between an anesthetist and a drug lord :
Once more thanks for your prompt response and support :bow:
Best Regards
Bob
Thanks very much for your comprehensive response to my queries.
Yes, the last 1/8" is free of thread; and no there is no recess in the bottom, (will fix that tomorrow).
Lamp oil in its natural state is in fact 300 test kerosene used in Hartridge machines for setting diesel fuel pumps and injectors. (A snippet from Bob's glossary of useless knowledge). The perfumes and dyes added by various religious orders definitely reduce its' performance as a fuel.
I hear what your saying about the contra piston. If I had to push any harder to get it into the cylinder, I would say it was a 1:1 interference fit - maybe that's whats needed ???
There is no dope in my mix, other than the dope doing the mixing :
When I remove the compression screw tomorrow I will be able to see how much fuel is under the head. There was minimal leakage around the screw and non down the sides between the head and cylinder.
It's good to know all CI engines are messy. I smelled like a cross between an anesthetist and a drug lord :
Once more thanks for your prompt response and support :bow:
Best Regards
Bob
Similar threads
