[47silver]

i think that the wur is more complex than that. i dont think it relies on force balance to achieve the mixture adjustment. i believe that since the heater is always operational, ( at least on my 1975) then the element is always being heated by this device. that made me think that there is a reason for this heater to be energized when the car is running.

if the engine heat was the method of heating up the bimetal then why would the heater be necessary as the engine heat or lack of heat would perform the same function, i.e. when the engine is cold the bmetal would enrichen the mixture when the engine is warm the bimetal would lean out the mixture.

the wur is more sophisticated than that, and i think that by using the heater a very innovative method of dynamic fuel mixture adjustment is occuring using differential temperature caused by the outside air and by the heating element. if this is not the case then the system would use a simple warm up thermostat to adjust the fuel after the engine warms up without needing the heater or all of the diaghrams and chambers.

that is why the wur is so confusing and can cause so many problems. if the heater is not working you will always be rich, try disconnecting the connection to the the wur and take it for a drive i would bet that no matter how long you drive (maybe in a very warm cllimate) the car will run rich. then reconnect the cable and see how it looks.

full power on the other hand to the wur only allows the wur to lean out the mixture when the outside air temperature overcomes the heater and the bimetal moves to the full lean position.

i may be wrong but i think that the people that designed this device were way ahead of a simple warm-up regulator.

gary