Ferret thermostats adjustable?

[LRDG]

Hi, I working on a Ferret at the Ontario Regiment Museum in Oshawa.

It's running well, but too cool.

I pulled the bellows thermostat out of a spare engine (Smith's RE15943, 30065/25, 73C, 163F) and found the valve disk at room temperature sitting about 1/16" off the seat. About the only reason I can see for that is the bellows has stretched over the years, or perhaps someone had been prying on the disk in an attempt to get it out of the housing). I can close the disk onto the seat by lightly compressing the bellows with my fingers. The bellows does not appear to be leaking as the t/s still opens up wider quite linearly when heated in a pan of boiling water.

I suspect the t/s in the running engine has the same problem (or perhaps it's been removed).

I see the disk on the spare t/s is threaded onto the valve stem (the stem that's attached to the top of the bellows) and soldered to prevent it coming loose. I'm going to remove the solder and see if I can correct for the bellows stretch by screwing the disk further onto the stem until the t/s starts opening at 163F and continues to open until about 195F (right now, that's when the top of the bellows hits the brass bypass passage block.

Hopefully these pics will make this clearer.

Has anyone tried this? Anything I should watch out for? I want the old girl to run at spec temp to avoid plug fouling, etc.

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