[Mgs] Jaeger Dual Gauge Modern Replacement Accuracy & Calibration

[Robert J. Guinness]

I bought a new "Jaeger" dual gauge for my MGA  from a vendor in 
England.  It looks great, but before I installed it, I wanted to test 
it.  I realize these are not precise instruments, but I was hoping at 
least be close to 212 (deg. F) at boiling without pressure.  I placed 
the entire bulb into boiling water (without touching the pot) at roughly 
sea level (453′).  I have tested original dual gauges this way and they 
all behaved as expected being near or at 212 when the water was 
roiling.  I also had a candy thermometer in the pot as a verification.  
The new gauge never got over a hairs width beyond 190.  The candy 
thermometer showed the correct 212 at a vigorous boil.  I performed the 
test again hoping the gauge was just "stuck" being that it was new.  I 
got the same result.  As the water temperature increased, the gauge 
appeared to read a somewhat consistent 20 degrees cooler than the candy 
thermometer.

I called the vendor and they intimated that I was crazy to test it the 
way I did.  Am I?  Is there a better way to test it without installing 
it?  Or is installation and an infrared thermometer a preferable way to 
test it.  Someone else suggested that you should simply move the needle 
to 212 at boiling.  But that is rather inelegant and the gauge would not 
go back to the resting peg at 90 when the car is parked.  How accurate 
should these gauges be, anyway?

Is there anyway I can salvage this unit without sending it back? Am I 
expecting too much?

Thanks.

-- 
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Robert Guinness

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