The winker on the Marshall Collection's 1918 735 has not been winking. It's definitely oiling, because there's plenty in the water tank & condenser. Unfortunately the people who have driven it recently don't recall if the winker is always showing brown or always showing the plunger face.

So I took a look into it last Tuesday - first time I had seen the inside of one. The plunger is an easy fit in the bore; in fact it rocks slightly more than I'd expect, but doesn't seem terribly loose. The spring seems very light. Spring pressure is presumably related to the winker's behavior, so we went to the parts bin and pulled out the spare winkers. All of them had a spring that was much stronger than the one in the 735.

Tom suggested that we take a look at the 1916 725, because its oiling system should be similar to the 735 - condensing car, thinned cylinder oil. (The 1922 740 uses a pressure gauge to monitor oil feed - no help there.) The 725 has the same light spring. As far as I can tell, it is exactly the same spring - slightly tapered on the ends. BUT - the hole in the plunger is larger than that of the 735.

I wasn't sure of the period of time when SMCC specified the thinned oil, so I thought perhaps the 725 was a transition and was oiled like the noncondensers. I then looked at the 607, the 76, and the 87 (1914, '13, and '12). They all had the heavy spring and the large plunger hole.

So I was unable to establish a pattern. Here's the data:

735 - - - - - - - small hole, light spring
spares - - - - - -small hole, heavy spring
725 - - - - - - - large hole, light spring
noncondensers - large hole, heavy spring

What's the real equation for oil weight, plunger hole size, and spring strength, to yield a good solid wink?

Kelly

On our 735 the oil is visible in the winker if we use normal dark Morris cylinder oil. Some time ago we changed to Mobil full synthetic gear oil which works very well but is not visible in the winker, the colour being too light. Could your thinned oil just be hard to see?........ Kobus

No, it's nice and dark. We haven't switched to any synthetics.

Dear Kelly,
So far you have done a very thorough investigation into the different types of winkers and the where of it.
The first thing that I would have done is to clean the inside of the winker glass and polish the plunger where it contacts the glass, and then take the Stanley for a test drive to take a look. If you have winterized it, then that would change things a bit. You would have to wait until spring for testing out the winker.
There are three types of oiling systems that require the different winkers: The Manzell oiler, the piston oiler driven off of the cross head, and the slower piston oiler driven off of the rear axle. There are also a couple of different viscosity steam cylinder oils used. Then there are the non-condensing and the condensing Stanley’s requirements.
You have pretty well already answered your questions as to why and where the winkers are used. To recap from what I see in your findings and from my experience:
Non-condensing Stanleys used the heavier oil being pumped by shorter strokes at a higher cycle per minute. It requires a larger hole in the winker plunger, and also a higher spring pressure for a faster winker response.
The condensing Stanleys used the lighter viscosity oil up to the model 740, and the slower rpm pump is driven off of the rear axle. Therefore, to be seen, the hole in the winker plunger was smaller (thinner oil) and the spring pressure was lighter for a proper winker response at the lower cycles per minute.
It has been my experience in both condensing and non condensing Stanleys, that when you first start out cold, the winker glass goes to a steady black out until the steam cylinder oil thins out from the heat of the Stanley. Then they wink very well and are reliable unless you have a broken oil line somewhere. Also if the oil pump packing gets too loose or if there is a supply problem, then the winker will go bright on you and you will know that you should quickly tend to it. The duration of the wink will also give you a hint as to the volume of oil that is being pumped.
It is prudent to always carry an extra winker glass and a couple of winker gaskets. Once while on tour, I broke a winker glass, and a nickel filled the hole until we could find a replacement glass for it.
The fit of the winker plunger to bore should be non binding and still not sloppy. A sloppy plunger will not report as well when the oil is hot. A new winker plunger is easy to make on a lathe.

About 10 years ago I needed a good winker for my 1914 Stanley and I used the winker from my spare parts. While I was running, the spare winker would go black and would hardly come bright on me again. I took it apart and found that it had a spring in it that was about half as strong as my old winker. I traded springs and plungers and it is still working good today. The spare winker that I had must have been off of a condensing model 735 with the weaker spring and smaller plunger hole.