Omega thermocouples

[orlin steven jared]

> 	I bought the gauge from AutoMeter for about $75 (comes with the
> amplifier module) and then discovered they wanted another $100 for a
> thermocouple! So I called Omega, and tried an open-junction 1/16"
> K-type. It lasted about 10 minutes. I should have known that the
> vibration would break the little weld ball off where the wires meet
> (the actual thermocouple).
> 	Then I tried a 1/16" enclosed end, 321 stainless. This responds a
> little slower, but will last for about 3 months or so (not so good at
> $31 each). The end just burns right off, especially when doing lots of
> full-boost blasts at 1600 F temperature.

Omega supplies a lot of auto companies with thermocouples for exhaust
gas measurement.  I'm curious, did they recommend the 1/16" 321
stainless?  Are you running one in each header tube?

> 	321 is not supposed to do this. Omega thinks it's a combination
> of corrosive gas, extreme temperature, and vibration. They suggest
> going to a 1/8" (but this will slow the response). Also the stainless
> compression fitting is irreversibly bonded to my exhaust manifold
> despite the use of copper anti-seize paste...

Sounds like you need a better alloy with more nickel and vanadium?

> p.s. I usually saw about 1050 F at idle (retards to 1 BTDC for lower
> idle emissions). About 1250 F at part throttle cruise, and up to 1600
> =46 at 15 psi boost. It's interesting to observe the effect of changing
> the AF meter flap tension on exhaust temps...


Wow.  For a naturally aspirated engine, I've seen temps at 500-600 F
at idle.



Steve