Warm Run Device question 1971 280 SE

[bracurrie]

If a 71C thermostat has been installed could the fact the engine never attains 80C keep the warm running device from fully closing to shut off extra fuel and air?
Valves, electrical, and timing have been checked and adjusted. But can't get idle correct. I observed that when the engine heats up in traffic to 80C idle drops from 8-900 rpm or so to 500 or so.
I have already decided to install an 81C thermostat, but thought I would ask if anyone had an idea about how the WRD works.
Brad

[bracurrie]

Answered my own question, but if anyone is interested the WRD( heat feeler) device should switch completely off at 65 - 70C. But after 1970 the heat feeler should switch off at 50-55C.

[bracurrie]

Received helpful information from a reliable source that explained something so useful I thought I would add it to my thread (no one else had comments).
The FI pump has a nifty altitude compensator (baro) that senses barometric pressure. The device extends a plunger as pressure decreases which decreases fuel. The impacts occurs to the system even when Warm Running Device is open. The two work in concert on the control rack such that if the baro fails and the plunger extends fully the resulting mixture during warmup and operating temperature would be very lean. To this non-engineer, non mechanic with only a basic understanding of air density and fuel mixture this seems like a really clever way to keep the ratio of fuel to air constant. However, I learned something from the SL Pagoda Group. The baro cannot sense density as impacted by temperature. So colder air is denser, thus as a user on the site experienced an over lean condition just after WRD closed but before engine fully warmed that was corrected by adding a shim to the baro. The baro can only be adjusted properly on a Bosch test bench. The BBB only mentions that the device exists but only gives instructions on optimizing the WRD.
Man is this fun or what?