<VV> Thermister Swap

[John Beck]

Sounds like you might want to take on this project, Patrick.  I started 
down a similar road about 15 years ago.  It's a worthwhile project but 
it wasn't anything I wanted to pursue. Here's more or less where I left 
it.  A few things have changed.  There were no bare thermistors on the 
market that were close to following the curve of the one used in the 
Corvair.  I had not considered replacing the gauge nor was the Rochester 
unit you found available when I was looking.  Replacing the gauge might 
be a good option but it will likely mean sacrificing stock appearance.  
I don't think you'll be able to match the Rochester sensor to the stock 
gauge with just a resistor network but you should be able to get close 
with an op amp or two.  That's the direction I was going before I 
decided not to proceed.  If I were taking on that project today, I would 
think about using an Arduino processor, an A to D converter, a D to A 
converter and a LUT.  The Arduino is major overkill for a job like this 
but once it's in the car I'm sure you could think of numerous other jobs 
for it.  If you have the time, you might enjoy working out a solution.  
Have fun.  --J.B.



Patrick via VirtualVairs wrote:
> To all, I have been reading the feedback on the  ROCHESTER 3080-38
> TEMPERATURE PROBE that I happened upon while trying to save  a few dollars
> on the unfortunate shortage of affordable thermisters  situation. It is true
> that the $300 - $400 needed to purchase  an NOS AC thermister is
> prohibitive for many Corvair owners, and  the $80 or so necessary for a used one is a
> risk as well. In  addition, I well aware that this is the way it is in the
> old car business  world and hobby. For theses reasons, and others, I was so
> excited when  I discovered the new Rochester temp probe for $80 in the  2015
> Spruce Aircraft catalog and I recognized the possibilities that it
> represents.
>
>      It appears that no one here knew of  this so the Rochester 3080-38 is
> untested in a Corvair auto application as  of today of course. However, the
> good news is that there is VV confirmation that  this unit it is essentially
> the same dimensions including the thread size  as the AC thermister.
> Perhaps, this is half the battle right there. It is  also my understanding is that
> this thermister will work for us if  we match it to a compatible gauge,
> after all it is designed to measure head  temps in an air cooled engine. This
> discovery may help some of us save some  dollars and give us an upgrade to
> more efficient and reliable  equipment too. Though I have not researched any
> head temp gauges yet I  am hopeful the someone out there will try this set up
> and let us know how it  works, provide us with the costs, and let us know if
> it was worth the  efforts.
>
> Patrick Laus
>
> 64 Spyder Coupe
> Metro Detroit area
>
>
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