Farm Boy running

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The ignition system is home made, based upon information cleaned on this site. I can send you a board and instructions, not hard to assemble. A few have commented on track widths etc and suggested improvements. I have tested one for many hours on a test rig and it is still fine, in fact it is the one running the engine in the video. Besides I have several boards in stock as there was a minimum order.

If you would like one, let me know where you are and I will send one.
Thanks I am on holiday from this weekend for 2 weeks I will contact you when I return.
 
Just thought I would post a link to this short video of my Farm Boy I have been building it over the last year of and on and ran it for the first time the other day. I should say I have little experience of internal combustion, all my projects so far have been external combustion.

I would welcome comments and suggestions from all you knowledgable people. It is suggested in the building notes that acetone is a good fuel for this engine. This is what I have used, but it is not great to paint or varnish and as I plan to use both on the engine and base I can see a problem. It also has a tendency to rust steel, the needle valve on the fuel had a surface coating after the first run.

Starting is a bit tricky, the most reliable method I have found is to flood it, close the needle valve and then open the valve once it starts to fire. Needle valve setting is very sensitive an 1/8th of a turn one way or the other makes a big difference.

As I say in the video I suspect that it is running a bit slow, although I like slow running it makes it difficult to get going with the governor engaged.

Finally, I need to make a fuel tank and incorporate a non return valve. Does anybody have a design for one? I am thinking ball and light spring? I have made lots for boilers but they rely on high pressure to keep them closed, I’m assuming that a clack type valve would not work.

An interesting project so far, makes a pleasant change from steam. Now have to paint the engine, have a go at some name plates, make a base and a fuel tank. Then on to the next project, any thoughts?

Sounds really good.
 
I am making a Farm Boy as well and have a question. Does a bushing have to be make for the Push Rod Roller? The roller has a .125" id and the screw that hold it is a 2-56 screw.
 
Pardon my ignorance but is that a kit or castings? How might one go about getting the plans and or parts or castings? Thank You Ken
 
I am making a Farm Boy as well and have a question. Does a bushing have to be make for the Push Rod Roller? The roller has a .125" id and the screw that hold it is a 2-56 screw.
Hi
You need to make a 2-56 flat head screw to fit. The flat head needs to be thin enough to clear the cam gear. The diameter directly under the screw head needs to match the id of the roller bearing. The remaining length needs a 2-56 thread. I probably don't cover the making of this screw in my YouTube video series. Some content might be of use though. Just search 'Andrew Whale' on YouTube to find my channel and the Farm Boy build series.
Good luck!
Andrew
 
I have been experimenting with the Farm Boy. It runs fine but is very sensitive to all things mixture and fuel tank position etc. I made a tank with a non return valve and all was fine Then yesterday it would not run consistently. After some thought I went back to the lash up on the first test run- a small bottle with a siphon tube. Still sensitive to mixture setting but it will hit and miss reliably.

Second oddity is that Colman fuel which I am now using appears to attack silicon tube, the end that is in the fuel tank expands and becomes soft, this appears not to happen to the part not submerged. Very strange.

Any thoughts?
 
Hi Simon
Coleman fuel (Naptha) and silicone do not work well together. There are lots of chemical compatibility charts which confirm that. Viton is extremely compatible with Naptha and I use that for the piston o-ring. However, I couldn't find any Viton fuel tube. I use Nitrile tube instead which isn't fully compatible with Naptha, but I've not experienced any problems.
Hope that helps.
Andrew
 
Hi Simon
Coleman fuel (Naptha) and silicone do not work well together. There are lots of chemical compatibility charts which confirm that. Viton is extremely compatible with Naptha and I use that for the piston o-ring. However, I couldn't find any Viton fuel tube. I use Nitrile tube instead which isn't fully compatible with Naptha, but I've not experienced any problems.
Hope that helps.
Andrew
Thanks Andrew, it is interesting that whatever fuel used, there is a trade off, especially finding o rings and tubing that will work.

What do others use for fuel tube and O rings?
 
As for the cam roller, I've used a small ball bearing from the hobby shop or something that I've junked. The hole will be bigger but that fine, just turn a small bushing that looks like a"top hat". Then counter bore the bushing so that the cap head screw (I use allens) is inside the bearing and the flange on the "top hat" misses the cam gear. If you can't find an exact .312" bearing a little bigger won't hurt, just adjust the placement of the 2/56" mounting so that the end of the bearing is in the same spot.

Jim G
 

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I am making a Farm Boy as well and have a question. Does a bushing have to be make for the Push Rod Roller? The roller has a .125" id and the screw that hold it is a 2-56 screw.
I made a bushing to suit the I’d of the bearing
 
Pardon my ignorance but is that a kit or castings? How might one go about getting the plans and or parts or castings? Thank You Ken
JE Howell model engine plans has the Farm Boy plans He was the designer of this engine. Mine ran so smooth that built another on 20% larger an it too is a smooth running engine. They have very long miss cycles for the size of the flywheels. Had brass ones casting in Amish country.
Harvey
 
A quick update on my Farm Boy.

It has had a few hours running and now misses for about 15 cycles. This seems to have made the fuel tank position and mixture more critical than before. The photo shows the position of tank relative to the fuel mixer. I did make a non return valve, but this seemed to make things worse.

BBACD4E4-E51B-4109-8A57-65C971ED5EC3.jpeg


From cold I open the needle valve just less than one turn, then choke for one induction stroke, the engine will fire first time but will stop after 2 or 3 cycles. I find if I help it along by half chocking the intake for 30 seconds or so it gets into its stride and settles down. It is then possible to lean the mixture to about 3/4 of a turn. If it is too lean it may take 2 cycles (i.e. 2 induction strokes before it fires, same thing happens if the tank is lowered. Do others find these fuel systems so sensitive?

I have now pulled it apart ready for painting. Will post some pictures when it is back together.

Simon
 
Hi Simon
I'm no expert but your fuel pipe doesn't look right with it looping upwards. On mine I put the fuel tank outlet at the bottom of the tank and level with the fuel mixer intake. The fuel pipe loops down. My fuel mixer is set at 3/4 turn and never needs adjusting. She freewheels 20+ revs between firing.
Hope that helps.
Andrew
 
Hi Simon
I'm no expert but your fuel pipe doesn't look right with it looping upwards. On mine I put the fuel tank outlet at the bottom of the tank and level with the fuel mixer intake. The fuel pipe loops down. My fuel mixer is set at 3/4 turn and never needs adjusting. She freewheels 20+ revs between firing.
Hope that helps.
Andrew
Thanks Andrew,

I think the commonality is that the tank needs to be quite high, relying on a non return valve does not seem very effective.

The final version of my set up includes a method of varying the height of the tank. With the tank quite high I found that there is a tendency for fuel to siphon. I think my logic is sound in that it matters not where the pipe goes, the important thing is the relative head of fuel. I am sure somebody on this site will give us the answer.

Simon
 
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