Amanco hired man

[Jasonb]

I would think you still need some form of carb to create a venturi to draw the gas into the carb. Its not good practice to have the gas bleeding in all the time, better to have a demand regulator which senses the slight drop in pressure due to teh venturi effect and open to let a little gas through.

J

 

[Brian Rupnow]

there is a lot of information about running an engine on propane here, including a "demand valve.
http://www.homemodelenginemachinist.com/f26/propane-i-c-engines-20266/

 

[fourstroke]

Thanks for the replies
I guess I didnt explain enough of my plans
I have the drawing for the regulator in the last link and was planning to connect that to the gas supply before it was connected to the engine
I am also planning to have the carburetter shown on the plans fitted but wont have any liquid fuel supplied if it is running on lpg but the opotion would be there to switch between fuels
My main queery was to whether anyone thought it would work in this configuration
Thanks again
Dougie

 

[Brian Rupnow]

Dougie--I'm lost now. First, you want to make a normal, standard, gasoline fuel carburetor with a needle valve to run your engine on gasoline. Then you want the option of running it on propane with the demand regulator also. I don't know if the propane line would then hook onto the same inlet that your gasoline originally flowed into or not. I think it does, and that you just have a different needle valve setting to run on propane. Your engine still needs the normal air inlet to pull air in and mix with your propane in the cylinder. You need the oxygen to support combustion. Pure propane won't burn. Maybe someone who knows if that is correct will jump in and set me straight if I have it wrong.----Brian

 

[fourstroke]

Hi Brian
My thoughts were to feed the propane, through a regulator , into the engine via the 4-40 hole that I highlighted in the last pic in the post where I asked this question
I propose to run the engine on lpg drawing only air through the carb with the liquid fuel shut off. This will mix with the lpg coming through the 4-40 hole and suitable pipework
If it is running on gasoline then the fuel would be fed to the carb in the usual way to mix with the air. In this case the lpg would be shut off
I hope this makes things clearer
Dougie

 

[Brian Rupnow]

Doug--Without the plans for that particular engine, I can't say whether you can or not. my gut feeling is probably not.---Brian

 

[idahoan]

Hi Dougie

I think that it would be best to pipe the propane into the same spot as the liquid fuel; If you use the location that you are talking about you will probably have enough vacuum to open the demand valve and pull fuel but no way to meter it. The propane needs to have needle valve control just like the gas would.

You would some how need to match the air flow to what ever non-metered amount of propane the vacuum from the engine pulled in; this in my book would be way to much fuel air mix to run the engine.

My experience has shown that the air/propane ratio in much more touchy than liquid fuel/air mix. If you plan to install a second needle valve to control the flow of propane into the engine, it may work; that is if there is enough vacuum to open the demand regulator.

Dave

 

[fourstroke]

Hi everyone
I thought I better update you on the progress on the engine

As the title suggests it hasnt all gone well and I need some advice

Anyway, I didnt like the idea of fitting a set of auto points to this engine so I have been following a thread on this site about a hall sensor circuit for model engines
I built this and the pics show how I fitted the sensor into the cam gear with means to adjust the firing timing, the gear has been cut in a couple of places, thats because the first set up was done off the cuff and when I put things together the sensor hit the cam so I had to re do stuff

So I put all the parts together, connected up the electronic bits and tried to start the engine, after a couple of spins the dam thing fired, ran for a bit then stopped. A couple of tweeks on the throttle and she was away, I hope the video of it running loads up OK onto the site

After a bit of running I dedcided it would be best to put a little water into the hopper to keep it cool, I ran it dry at first as I wasnt expecting it to run like it did, my son is in the background feeding fuel into the engine

Well this is where the despair comes in and where you guys and gals out there come in with advice

I have hopefully uploaded a video of the situation, with water in the hopper there suddenly appeared a lot of bubbles when turning the engine over and the water level dropped, anyone want to guess where it went?
Yup thats right, into the cylinder.

On dismantling the engine I find I have a pinhole from the bore through to the water jacket. Its tiny, I only found it with a hard look but its there.

I hope, and this is your part, that I might recover the situation by coating the inside of the water jacket with fiberglass resin, hoping it will seal the leak. The hole is too far round the cylinder to get at from the outside and too far down the bore to get from the inside, its right at the point where the cylinder wall meets the mounting flange, almost underneath

I just got a message I cant upload video, can anyone tell me how to do it, this is a link created by my pet computer genius
[ame="http://youtu.be/Rx4vsZP8QKQ"]http://youtu.be/Rx4vsZP8QKQ [/ame]

[ame]http://youtu.be/VMQ8hrHAFZw[/ame]

[ame]http://youtu.be/yX0HcGglSGk[/ame]

Anybody out there with any suggestions please get in touch

 

[bobsymack]

Hi
If I were you I would try some chemical metal like devcon rather than fiber glass I have seen this to successfully repair a frost cracked cylinder block or else you could maybe re sleeve it if you have enough meat to bore it out.Hope this may be of help .
Regards Vince

 

[Jasonb]

Take a look at some of the fuel tank repair/lining liquids these are said to seal pin holes in rusted tanks. POR15 is the most likely candidate

http://www.frost.co.uk/por15-basic-car-tank-repair-kit.html

 

[fourstroke]

Thanks guys
The fuel tank sealer looks good but its a bit expensive

The chemical metal might be OK but I cant actually see where the holes are,
( I now know there are three) as they are too far round the water jacket

My thoughts today are that I need something thin enough to fill the tiny pinholes. To help with this I plan to put the cylinder under a little vacuum to try to pull the sealer through to the inside of the bore

I am looking for something with the consistency of paint that wont set too fast, the fiberglass resin is probably too quick setting

Superglue has crossed my mind, thin enough to fill the holes then perhaps some epoxy on top

J B weld might be ok but I might need to heat it a little to make it "runny" and that might make it set too fast

Any thoughts

Dougie

 

[fourstroke]

I have managed to seal the pinholes in the cylinder with epoxy and now need some advice on the best fuel to use
I have tried straight unleaded petrol and also a mix of ether and unleaded which works quite well
I have read on this site about the use of coleman fuel, can anybody tell me what this fuel contains and why it is better than normal unleaded
Thanks
Dougie

 

[Jasonb]

Probably easier to read this thread then post it all again.

http://www.homemodelenginemachinist.com/f16/coleman-fuel-21959/

J

 

[idahoan]

Hi Dougie

I have had good luck with wicking Loctite (290) and primer; you will need to get the pin hole clean some how. Probably by forcing or vacuuming some solvent through the hole then followed by the Loctite primer and after it drys then the Loctite.

Sealing porosities in welds and castings is one of the intended uses for this product. The nice thing is there is no build up of material on the out side like you would have with the other materials.

Dave

 

[hotrod]

The POR 15 should work fine for you problem. In my shop I have resealed oil coolers , carberator brass floats , corroded aluminum carb cases ect . If you have not used the product my advise is by the small cans, stir don't shake to keep bubble out of the finish and when you reinstall the lid you will have to abuse the lid to remove if any residue was left in the cap to can seal groove. I no longer remove the lids and use a self tapping screw to puncture a hole near the edge and to reseal when finished. It has a long working time and cures to a almost ceramic hard finish.

 

[fourstroke]

Well, after a long let off when I was restoring an old Aster engine, an email from Jason B reminded me that this model needed finishing
I have attached a couple of pictures of the engine painted and on its stand
The ignition is by hall effect using the circuit posted on a thread on this forum, the magnet is mounted in the cam gear
The darker wood on the base are covers for the battery and ignition pcb\coil so that the unit is self contained
I will post a link to a video of it running later
Regards
Dougie

 

[fourstroke]

this is a short video of the engine running, here is the link : http://youtu.be/XfVuwZjes64?list=UUL9rLbP3w_rfJmAAEB8CHrA
Dougie

 

[Jasonb]

Starts and runs very well Dougie, glad I gave you that bit of encouragement to finish it off.

J