<VV> CHT data calibrate

[FrankCB@aol.com]

        I definitely agree that CHT gauges (or any other temp gauges) need to 
be calibrated.  But depending on an oven temperature control seems way too 
likely to be inaccurate.  Perhaps you could use the IR gun to measure the actual 
temp of the gauge sensor coming out of a 400 to 500 degree oven and then 
compare that to the gauge reading.  But remember that you have to hook up the 
gauge/sensor combination to a 14.2 volt DC power supply to get a setup that will 
be equivalent to the same operation in the running car.
       When I checked the calibration of the Stewart Warner CHT gauge that I 
installed in my Monzas, I used gauge unit installed in the car with the sensor 
immersed in a silicone oil heated to 350 deg.F.  The sensor was temporarily 
attached to a laboratory mercury thermometer and the two were stirred in the 
hot oil.  I put on a battery charger set to maintain 14.2 volts on the car's 
electrical system (engine was off).  The calibration was dead on at 350 deg.F 
which was the middle of the dial on the SW gauge.
       As far as using the IR gun to read directly on the cylinder head I 
don't see how you can do this while the engine is under load unless you've got 
the car on a chassis dyno.  Sure you can do this at idle speed, but you'll then 
be far below full load temp.
       I would recommend instead using one of the 2 methods in my the first 2 
paragraphs above.
       Frank "ALL Corvairs need CHT gauges" Burkhard

In a message dated 10/25/04 3:46:19 PM Eastern Daylight Time, 
SadekCH@NSWC.NAVY.MIL writes:

> One of us ought to put a head or sensor in the oven, hook up the sensor and
> gauge and see what the heck it says; i.e. calibrate it!  At least for that
> situation in that location and temperature, we would have an idea... 
> 
> My prediction...kind of like Johnny Carson.... is that the temp will be
> within plus or minus 20 degrees but we will still have no way knowing what
> air flowing by does to cooling the thermistor....
> 
> Really need two ovens, one for the gauge that we can adjust from whatever-in
> my case, 50 degrees under dash to 120 degrees.
> 
> Chuck S