[alfa] Spider 120 MPH Speedometer & Idle Actuator

[Otto Schug <schugof@xxxxxxxxx>]

Alfisti,
 
I have an 82 Alfa Spider.  It had an 85 MPH speedometer that was optomistic in its speed results.  I acquired an 84 Spider with a 120 MPH speedometer, but the trip meter would not work because of the rust in the coaxial cable.  Therefore, I bought a used 120 MPH speedometer.  Unfortunately, this speedometer is optomistic and sets at 13 MPH at idle and 10 MPH with the engine off.  It would appear the difficulty is not in the speedometers, but in the device in the engine compartment.  I cannot find any reference to such device, except that it exists, in any of my Workshop Manuals.
 
How do I fix the problem so that I know my actual speed?  Both speedometer needles jiggle until I get over the "seat of the pants" speed of about 50 MPH.  Where to I find a Manual dealing with repair?  I am aware the device is permanently affixed in the engine compartment to prevent "turning back mileage".  Where can I get a replacement device?  You understand my dilemma, so if I haven't asked the right questions, be so kind as to provide the answers appropriate.
 
The Spiders have an idle actuator to adjust the idle based upon temperature.  Such device is located on the right rear top side of the valve cover with one hose going into the crossover hard rubber plenum, the rear hose going into the airbox and an electrical connector at the rear.  I have three of these devices.  At room temperature, one of them is almost closed, one of them is slightly more open and the last one is open substantially (about four times the area of the first one).  What is the proper opening at room temperature?  I have frozen and heated all three of the devices; each device remains constant to its opening and closing factors.  Where do you find data concerning the devices?  In addition, with the current on, the ground wires attached to the bolts affixing the device to the valve cover spark.  Why?
 
Please advise.
 
Otto F. Schug
My son and I have about 13 various running, in adjustment and parts car Alfas
schugof@domain.elided
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