<VV> Cyl. Temp. Gage

[Dave Thompson]

>From personal experience....

My CHT gauge failed. I replaced the thermister and all was good. A few
hundred miles later, the needle started to jump around. After some watching
I realized that it jumped around when there was movement of the engine, such
as hitting bumps or a good rev of the engine. I pulled the lower shroud and
found that the tiny 4-40 nut holding the ring terminal on the thermister had
come loose. The terminal was bouncing around on the stem with a loose nut. I
couldn't use a nylon lock nut due to the heat and the nylon melting (I
guessed). So I went to the model airplane store and found a 4-40 crimp nut.
I'm not sure what the proper name is but there is a tip on the nut that
resembles a nylon lock nut. The tip has slots cut in it and works the same
as a nylon lock nut. However it is all metal. I installed it on the
thermister to hold the wire and I haven't had any problems since for several
thousand miles. Also check to be sure that the threads are clean and rust
free. You need a good electrical connection on the wire.
By the way, a thermister can be tested by measuring with an ohmmeter between
the large threads and small threads at each end. You should get something
around 500 ohms at 70 degrees F. As I'm sure you know the gauge is not
accurate. You just find out what is normal for your car and watch for
something abnormal before you get alarmed.

Good luck. 
Dave Thompson
63 Spyder vert
Westminster, CA