Stock s5 Water Temp Gauge Scale?
 

Has anyone calibrated the stock FC temp gauge scale, as in this FD cooling thread?

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/big-fat-fd3s-cooling-thread-571088/

I'm aware of the "normal" temp reading for s5 & s4, but was wondering if anyone knows what temps correspond to the scale marks.

(I don't intend to rely on the stock gauge, but I had no choice when my Autometer gauge failed.)

Does FD and FC use same gauge?

I haven't done any calibrating, but based off of information in the FSM, the bottom is 50 degrees C, and the top is 130 degrees C. Assuming linearity of the gauge, which is a big assumption, that puts normal operating temp around 90 degrees C, which seems almost right.

It's a GIANT assumption and in the case of the S5, incorrect.
The S5 gauge reads NORMAL (at the center) from @160°F to @230°F.
It's more of a dummy light than a gauge, really.
By the time the S5 gauge looks like it's reading HOT, it's already too late.