Correct CHT probe for a Rotax 277?

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larrygmoody

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Which CHT probe is the correct one for a Rotax 277?

From what I've read, the type "J" is the correct one for the applicable temperature range, but I cannot seem to locate a probe with the circular ring to go under the spark plug (although, I did find a type "K" with that end).

Also, what size ring is needed? 10mm? 12mm? 14mm?

Thanks in advance!
 

BJC

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Type J TC’s are common, but some instruments use Type K.

Best to look on the back of the instrument and see what it is designed for.

BTY, when I was a co-op student working at a power generation plant, I made, literally, hundreds of TC’s. The costs today are really high for what is involved.


BJC
 

larrygmoody

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Yes, it does. And all the connections are male, so my new one needs female connectors.

So I'm looking for a 14mm, Type J or K, CHT probe, with female connectors.

Seems to be a rare breed. All I see are spade connectors or bare wires. I'd rather buy the correct probe than solder one together.

Thanks

Edit: ----

Found this one at Aircraft Spruce (just the probe): Westach Engine Analyzer 6 Cylinder CHT Kits 14MM | Aircraft Spruce
 
Last edited:

Dana

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You're supposed to use an extension cable with female connectors on both ends. Usually it comes with the gauge,

 

Dana

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The 4ft lead has the same bullet connector as the instrument. You will need the extension with the female connectors.
Exactly, you need the extension to make the connection, whether you need the length or not. Any excess, you coil up and tuck out of the way.
 

larrygmoody

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<sarcasm>Wonderful! <\sarcasm> The picture looked like female connectors, but it wasn't clear. Plus the old one has the female connectors, so I assumed... Well, you know.
 

Bob H

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Jun 9, 2022
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Type J thermocouples are used for applications below 700F and Type K are used for higher temps like EGT in the 1500F range.
The readout device has to match the TC type. I make my own CHT probes using a copper washer with the J leads soldered to the washer.
The washer is placed under a bolt in the cyl head of a Rotax 912 and works well.
 
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