Deve,
Your interpretation of the flow pattern before and after warm-up does not make sense, but your interpretation is the same as mine.
Feel free to use the photos, just give an attribution-reference somewhere.
The measurement of the diameters of the two different thermostats are posted above, I think:
2.125" (2 1/8") for the 235 (all years) and
2.500" (2 1/2") for the 261, at least for my years (1959-1960 -- my guess is 1958-1963, but I have no documentation to back this up).
Do you want other measurements?
