Farm Boy 651

[Brian Rupnow]

Rudy--Congratulations on your first gear. That is a big step upwards in your engine building path.---Brian

 

[Rudy from Norway]

Made the head. Not any difficulties. The valve guides/seats are more critical. Turning the pocket and guide hole in one operation to ensure accuracy. The fit to the holes in the head is 0,03mm oversize if I managed to measure right. Pressed them in with the wise having a sleeve over the guide to press against the thicker part.
The valves are probably the hardest part to make in the head assembly. Like TinkerJohn on JouTube says, 50/50 chance to get them right. I believe making them in two pieces is harder to get straight compared to turning them from one piece. However, it was too attempting to do the two-piece version. It is an easy way if it gets straight. I actually Locktited the valve heads and stem together. Adding to the believe that it will hold I made some dimples at the end. My impression is that Locktite 603 is very strong until it let go with a snap. With no hard knocks and no very high temperatures, I’m willing to take the chance. If someone having experience here, I’m grateful for feedback.
The reason I didn’t silver solder them is that I guess I would have to make a running fit to get some solder inn between. I made a tight fit to have no play and hopefully maintain the parallelism with the valve stem. I have good experience with Locktite and tight fit.
At least they look nice and when testing in the head, there is actually no leaks when I’m blowing in the ports. That before the valves are lapped.

Rudy

 

[Brian Rupnow]

I don't think that the Loctite will hold up on your exhaust valve assembly. I have made many one piece valves and it is not terribly difficult. the hardest part of any valve is getting it to seal properly in the valve seat to enable good compression in the engine. I struggled with this HUGELY until I found a plan for the George Britnell valve seat cutter. Since I made one of them, I haven't had any real problems.---Brian Rupnow

 

[Rudy from Norway]

Thanks again for the feedback Brian. I started with two-piece because it was so easy. A piece of rod and a little disc. The plan was to silver solder, but I hesitated. If the valve head gets loose, I probably will damage the crank and more, so I will make one-pieces. I have done hundred car valve jobs, so I have an idea of how things work.
My goal is to make the seats and valves right and having them tight without the need for lapping.
To achieve that I figure a straight valve is the key to success. If I have a straight valve I can always lap down the seat if it’s not straight. Or I can make it straight with a good reamer. However, I can’t straighten a hard valve by lapping, because the soft material in the seat will give before the valve. The valve will probably never seat properly if not straight. Right?!
In this Farm Boy engine, the valve guide and seat is the same part that is turned in one operation. This makes it easier to get them in line to each other.

Rudy

 

[Rudy from Norway]

Tried to make one-piece valves. Ended up turning a couple of tapers. Reverted to the study and did some research. Came across your valve tutorial Brian . I’m going to try it. However, I also going to try another method I’m thinking of. I’ll let you know..

Rudy

 

[Rudy from Norway]

I have great progress in this build and I will come back and post many pictures, but I’m stuck now and need some help. The governor catch lever shall have a hole for a speed adjustment screw. I don’t understand how this screw shall be made or how it works. The plans are not very clear on this. At least I don’t get it. Is it an adjustable spring pushing the lever out? If so, why not just a grub screw with a spring in front?
Grateful if someone could help me out here.

Rudy

 

[Engine maker]

Yes you probably could just tap it and use a screw against the spring, but if you back the adjustment screw out you may loose the spring. This way the spring is captured and can only come out one way but is blocked by the limit of the arm's movement. Also if you use the threaded barrel you have more room for a longer spring which gives you more adjustment.

By the way, a good spring to use in this place is the spring from under the flint in a BIC disposable cigarette lighter. I built Serial #003, the first one other than the prototype and it still runs great. It now will coast + 70 revolutions between firings and on a good day I can get it to do + 100.

 

[Rudy from Norway]

Think I got it Engine maker. The screw body in the plans is going to be pressed into the widest part of the hole and stay attached (plans doesn’t tell). Preferably with some LockTite. Then I have a clean hole for the spring with no threads for the spring to catch up on. And the spring, as I understand, shall press the arm out from the latch. There is no spring in the plans, so I wondered.
So you have built one your selves! Just had a glance at it. Looks like a real show piece. This is as far as I can tell, a very well-constructed engine. A pleasure to make. Lots of machining. Easy to correct if you go wrong (compared to a casting kit). This is my second build and I’m so eager to have it running. I do everything as accurate as I can, so I expect it to run well.
What is the secret to make it turn 100 times between hits?
Rudy

 

[Rudy from Norway]

Think I got it right. Maybe the spring I have here is a bit small. One other detail.. the screw for the catch block is drawn in the plans at a 4 degree angle to the block. That will easily brake the small screw if it is tightened. Fixed that.

Rudy

 

[Johno1958]

Rudy that's one hell of a good looking engine your making. Great work.
Cheers
John

 

[Engine maker]

You can also solder the speed screw adjustment body in the arm. It takes just a touch.

Yes, It's a great engine to build. It will coast 30- 40 revolutions as the norm. I made 1 or 2 minor changes that I'm keeping secret ( how else will I keep my status as a "Miracle worker")? But I'll give you a hint, you have to go on a MAJOR drag reduction effort. I also found out that mine runs much better on Coleman (camp stove fuel) than on alcohol or acetone.
Can't wait till you let us know it's done. You'll enjoy it!

 

[Rudy from Norway]

Engine Maker, I want to earn my selves a nick name to! I will pick you up on that 100+ revs! When I succeed, I want some fancy name. My first build, the Stuart 10V, runs on 0.4psi with no running in, so I’m feeling I can manage it with even more practice. My “thing” is accuracy.
I noticed Jerry Howel wrote something about Naphtha as fuel. Have a bottle I will try. I also got the plans for the Propane demand valve. Like the Propane idea because of the very clean exhaust and no soot.

Rudy

 

[Rudy from Norway]

Some progress in the build. Got to try my new Soba 8” rotary table. After having two crap tables this one is way better. A bit large, but you can still use it with small parts. Very rugged. Made the cutting tool for the gear just free hand on the grinder. Of cause not very correct profile at all, but I believe it will work. Also remade the valves from one piece after the Brian recipe. Made the rocker arm a bit more ornamental than the plans called for. Thought it was wort some extra just for the looks. After all, it’s the main part of the “jewels”.
Another feature I added was offset bearing split on the connecting rod big end. I liked the idea of having the con rod support the bearings, not just the bolts. The second last pic shows the split in offset to the bolt grove. The last pic shows the setup to get the two groves for the bolts in parallel.
Summer is coming and lots of other activities waiting. The progress will be slower now. I have never been looking forward to the winter like after having taken up this hobby..

Rudy

 

[LorenOtto]

I am enjoying your posts very much. Keep up the good work.

 

[Rudy from Norway]

I’m back in the shop after having most of the summer holydays with all kinds of other activities, behind. Had the fly wheel blanks ready and started to dig into them. Figured the best way was to screw them on to the surface plate. The chuck isn’t big enough, so it had to be this way. Faced of the plate to ensure it will run true. I had recently bought an 8” rotary table that came in very handy despite being a bit large for my mill. Don’t regret that now.

Rudy

 

[natalefr]

WOW !

 

[minh-thanh]

I think it will be very beautiful when finished,!!

 

[terryp]

Hello Rudy, Working my way toward a hit & miss so watching your thread with interest. Looking at the date stamps on your photos makes me slap my forehead in amazement. it would take me forever to do what you have accomplished in a month or so. You make it looks so easy.... truly an inspiration for us amateurs! Of recent interest is your flywheel. I was trying to figure out a tapered spoke flywheel but yours looks great. I do have a six inch rotary table so that will be the tool of choice for the setup. Thanks! Terry from Texas

 

[Johno1958]

Hi Rudy , good looking flywheel. Roughly how long did it take to machine?
Glad your back at it .
Cheers
John

 

[Rudy from Norway]

Terry, I started this build last winter, spent a lot of hours at it. However, the summer calls for other activities. Feels good to be back in the shop though. I will pick up the pace towards the winter.
John, it took a while to make the first flywheel. The material is some kind og hard cast Iron. I did not manage to mill sideways, so I did many small increments of plunge cuts before going sideways to make a smoother surface. Made up a sketch with all the degrees to all the holes, used my DRO and tested all hole positions before I did drill the holes and started to mill out the spokes. Guess a week on each, all in all.

I really love building this engine. A lot of machine time. Started to think about the color scheme.

Rudy