Excessive motion of the valve when in mid gear

Hi there folks,

I hoping someone will have some ideas for me. I seem to have excessive motion in the valve when in mid gear (about 9.5mm). This motion is just enough to open the steam passages to the cylinder by about 0.5 to 1mm each side. Not a major issue but gets a bit hairy on the occasion a piece of crap got under the regulator and I couldn't close it off. The engine ran in reverse and there was nothing I could do to stop it save dropping the fire and waiting.
I have spoken to Steve and he advised the test model only had about 6mm movement when in mid gear. If I could drop the extra 3.5 off my engine then the steam passages to the cylinder wouldn't be exposed.
What are other builders experiences?

Any help/thoughts much appreciated.

Cheers Andrew

Hi Andrew,
Mine has about 5mm movement in mid gear and doesn't run in that position.
How did you determine your mid gear position?
I did mine by moving the reversing lever and rotating the engine by hand until the movement was minimal then marked this position - the die block should be close to centre of the expansion link. Then moved the lever to full forward and rotated again so I had clearance allowing for thermal expansion. The 2 notches between full and mid where then marked - the one closest to full to Steves dimension but the 2nd notch based on the lubricator actually incrementing. Reverse was done same as full forward.
Hope this helps

Graham

Hi Graham,
From memory (and admittedly thats bad!) I followed Steves instructions for the initial setup.
Several of the "old hands" down here have had a nosey and the general agreement is the mid gear is about as good as can be. Even moving it back and forward a bit doesn't make much of a difference in the valve movement.
It's interesting the amount of movement you are seeing ties in with what Steve saw on the control model (and a mate over here who has a 4" clayton shuttleworth with similar valve setup also sees about 6mm movement)
Steve sent me the diagrams for the eccentrics so I could verify they were correct as that was our first assumption as to where the fault was - but the eccentrics are correct.
Unfortunately, none of that explains the extra movement in my engine.

Did you find an answer to your problem? I'm building a kit of a similar vintage (don't ask, its taken longer than expected!) and have a similar problem in mid gear the ports are being exposed.

HI There, did you find a solution?

Will confirmed that my engine was the same as their control model at the factory. One of the members of my ME club is going to have a look to see if he can see anything wrong over the winter.

There has to be a difference somewhere between the crankshaft and the valve.
It's just going to take time and a comparison engine to work out what the difference is.
We have the NZ biannual model engineers conf coming up in January only a 1/2 hours drive from me so I am hoping one of the other agri engines here in NZ (there are only a handful in the whole country) will be there and I can get some time to do a close up comparison.

At this stage I’ll have my agi at Hamilton for u to have a look at

Kiwi,
Just had look on mine, there is around 9mm of travel in mid.
I tried to adjust but didn't seem to make much difference.

Barry.

Good Afternoon, I appear to have the same problem, did you find a solution.

Thanks.