Stephenson valve setting

[jlakes85]

Hi Brian,

Right now the engine runs very similarly to how yours did when you posted the video of the first test on air. Did you have it timed correctly at that point? John makes a great point about not having a flywheel or trucks attached to dampen irregularities

-john

[Brian Hilgert]

Hello John, I did not have it timed correctly at that point. If I remember correctly, that was late night/early morning and I just wanted to see it turn over for the first time. I have since went back and adjusted the location of the slide valves only. I never went back and tried to adjust the eccentrics. I probably should revisit it. I have a video on it running at cabin fever last January. Let me see if I can post that video for you.

[Brian Hilgert]

https://www.youtube.com/watch?v=StVFWE1 ... e=youtu.be



Not perfect, you can hear it in the "chuffs"

[Soot n' Cinders]

Tristan,

Regarding the bind that your engine had, where did you trace it too and what was the corrective action?

When I finished mine, everything was really tight and it took a few hours running on the lathe until I felt confident I could bar the engine over by hand, but there might still be a sticky spot. Thanks to all for the input.

-jlakes85

Mine was tight at first too. I ran it in for quite a while, using kerosene as lubricant while everything worked in. Once it stopped running hot I put 90W gear oil on everything and it's been fine since.

[jlakes85]

https://youtu.be/TVpx5Wm6XV4




Above is a link to the air test. How does everything sound?

[Soot n' Cinders]

It's pretty square on the timing. To me it sounds like it just needs to be run in some more. Put some WD-40 or kerosene in the bearing and let her rip. Will probably take 20-30 minutes of the running with cleaning in between to get everything smoothed out.

[jlakes85]

I had to make some changes since this last video and after talking to John.

I'm still scratching my head overall as I had to really offset the one pair of eccentrics as shown in the attached photo, to get the top power port just cracked as the engine reaches TDC, to achieve early admission. The crank is set to spin counterclockwise looking at the photo

When I tried to set things as per the drawings, I seemed to keep getting late admission by about 15 degrees or so. I didn't have an ideal setup at my disposal but I was able to somewhat verify correct eccentric position by moving the link through its full range of movement at TDC and verifying no movement of the valve.

The engine will run well in one direction but not at all in reverse. I checked the pinning arrangement and rechecked the eccentric offset jig and the distance from the bore to the edge of the eccentric is the correct 0.669

Also they were mounted on the crankshaft with the V facing upwards at BDC as per the drawings. Also the distance between the crankshaft center and the link pin is the correct 7.915 at BDC.

I've noticed that at BDC the valve is perfectly centered, with the eccentric V facing upwards, but this is not the case at TDC where the V faces downward, which seems to make sense since the crankshaft center to eccentric maxima distance will change proportionally.

The eccentric straps are still somewhat of a tight fit so I'm not worried about slop at this point. Any suggestions as to what might be going on. Greatly appreciated as always.

-jlakes

[Soot n' Cinders]

That sounds like the valve is not centered over the ports.

[Fred_V]

If it won't run in rev. I would look at the rev. eccentric position.

[jlakes85]

Fred,

I'm thinking I'll need to un-pin the eccentric on that side and set the front and reverse ones separately. If worse comes to worst, the can always pin them back together

[Soot n' Cinders]

Fred,

I'm thinking I'll need to un-pin the eccentric on that side and set the front and reverse ones separately. If worse comes to worst, the can always pin them back together

I set mine separately, just held to the shaft with a set screw instead of being pinned together. That will give me the ability to adjust them separately again later on if need be.

[jlakes85]

Sounds good. I'll probably have to go that route on the one side for whatever reason