[Dave Hottmann]

The C-16s and C-19s are basically the same when it comes to tuning.

3 basic adjustments
Johnson bar- Neutral is neutral
Eccentrics- Equal forward and reverse
Valve adjustment- Equal 3 and 9 o'clock admissions

Johnson bar
With the Johnson bar in neutral there should be no movement in the valve rods while rotating the drivers. If checking with air pressure in the boiler and the throttle open, driver's should not move. If there is movement, adjust the Johnson bar by loosening the screws at the base of the Johnson bar and move it forward or rearwards until neutral is neutral.


Eccentrics
Place the Johnson bar in forward. We want to center the eccentrics for equal forward and reverse. With the rod pins at 6 o'clock, the large end of the eccentric should be all the way forward on the same side of the engine. When you rotate the drivers back and forth a little, there should be no valve rod movement. You can use the spokes as a reference to make sure when rotating the drivers back and forth the same amount, the valve rod starts to move. Make needed adjustments by loosening the 2mm Allen head set screws in the eccentric and rotate as needed. A little at a time works best.

Valves
Place the Johnson bar in forward. We want to make the beginning of the 3 and 9 o'clock admissions equal. Either by compressed air or observing the ports. If eyeballing the ports, you want stop rotating the drivers when the port has just started to be uncovered. At this time observe the relationship between the side rods and the driver axles. On the right side of the engine the front port should start to open a little after 3 o'clock, and the rear port should start to open a little after 9 o'clock. On the left side of the engine the front port should start to open a little before 9 o'clock and the rear port should start to open a little before 3 o'clock. If using compressed air, load the drivers with your finger to see the beginning of the admission events. Make needed adjustments by loosening the 2mm Allen head setscrew in the valve collar and move the valve forward or rearwards a tiny bit as needed. Removal of the valve cover is nessessary to perform this adjustment. A short cut when using air is to use mini clamps to hold the covers on between checks, instead of installing the nuts.

All these adjustments have been for the best forward. There is no such thing as a perfect forward AND reverse, so try not to driver yourself crazy. Sometimes you have to take away a little forward to get an acceptable reverse.

 

[weaverc]

Dave,
Thanks, you made a couple of things clear for me. Do these principles apply to the K series locos also?

 

[rbednarik]

Carl,
The tuning for the valveblock is the same on the K-27/28/36, but the valvegear is of a walscharts design, unlike the C-16/19's Stephenson valvegear (in between frames), the eccentrics are actually functioning to move the valves, and are located on the crankpin of the main driver. Timing walscharts is actually a bit more straightforward. Take a look at my posting on the GS-4 combination levers, there's a bunch of information on setting walscharts there. I can send you a high-res pic of the diagram as well to clarify.
GS-4 performance link

 

[Dave Hottmann]

Special note. If your engine has a binding problem, tuning will be very difficult. I have had 2 C19s that would bind up at the upper crosshead guides in the front. I have been installing one 2mm washer (from the local hardware store, Hillmann brand, .3mm thick) between the guide and the gland o-ring retainer.