Water Temperature Gauge and Speedometer

[Otto Schug <schugof@xxxxxxxxx>]

Alfisti,
 
Several weeks ago, I bought an 82 Alfa Spider.  I attempted to drive it home some 200 miles.  After about 30 miles, the temperature gauge was reading 212 degrees and above.  Eventually, I gutted the thermostat and drove the rest of the way home.  Since then, I tried a lot of things (sender, thermostate, clean water lines, different radiator, etc.) to get the temperature down.  Earlier this week, I attached a mechanical sender into the heater hose line by the thermostat.  While the electric car gauge was reading 212, the mechanical gauge was reading 175-185, depending on the opening and closing of the new thermostat.  Thus, there was nothing wrong with the car in the first place, except a faulty gauge.
 
Now, (1) where do you get a new gauge?  (2)  With the three male electric prongs on the rear of the gauge, how are the connect - ground? sender? positive electricity?  (3)  What is the wiring to the gauge so that an external gauge could be attached near the engine to test the reliability of some of my collection of used gauges (4)  Can the replacement gauge be installed without removing all of the console items (The car has A/C)?  Can a mechanical gauge be installed?  (5)  If a mechanical gauge can be used, where can the temperature prong be inserted noting the electrical sender is 16 X 150 size and pitch? Is there a metric mechanical temperature system?
 
As to the speedometer (0-85 MPH):  It is very optimistic.  I would guess about 5-10 miles faster than the actual speed.  Nevertheless, what is required to put in the regular 0-140 MPH speedometer?  
 
Otto F. Schug    schugof@domain.elided
Chip and I have 11 Alfas, various engines and a lot of parts
--
to be removed from alfa, see /bin/digest-subs.cgi
or email "unsubscribe alfa" to majordomo@domain.elided