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Carb heat sensor. Yes or no?

Paul Tuttle

Paul Tuttle

Well Known Member
I've searched the forums and found that a lot of folks don't think the carb heat sensors are of much use.

My carb has a plug where the sensor is supposed to go and it would have to be drilled and tapped . I have the probe that came with the Dynon D-180, I'm undecided as to whether I should bother using it. I'd sure hate to ruin the carb if I messed it up.

I'm looking for a few fresh opinions.

Thanks.
 
I had a sensor and gauge during phase 1 and it was useful for evaluating a couple of configurations of carb heat. It was only useful during the first run-up of the day because as soon as everything under the cowl got heat soaked it always read high. I took it out later and used that hole in the panel for an autopilot controller and put the little plug back in the carb.

Paul Danclovic
Jamestown NC
RV-8A N181SB
 
Hello Paul,

My AFS Sensors came with a Carb Air Temp probe so I put it in. I used fiber washers to insulate the probe from the Carb Body and also used a little Teflon tape on the threads hoping to measure Air Temp rather than Body Temp. That point is above the jets so thinking it is safe to use the tape?? I’ll see how it works out. I like the Optical Detectors too, which would mount in the same hole, but are extra $$.

http://www.aircraftspruce.ca/catalog/inpages/icedetect2.php

http://www.aircraftspruce.com/catalog/inpages/icedetect.php

pk
 
My GRT carb probe reads carb body temperature. When I used a solder iron to touch the threaded part of the probe it read the same as the tip of the probe. Fiber washer did not help. I still have it on but do not trust it to give me the correct indication.
 
Paul,

Firstly you would need to know if your particular brand probe actually measures the air temp or just the conducted heat from the carb body in which case it would be almost useless IMHO.

I have a CT gauge with a JP Instruments probe which accurately reads the air temp rather than the carb body temp and I do find it useful.

With the very small standard Vans carb heat shroud on the exhaust there may be no noticeable rpm drop when carb heat is applied so the only way to know for sure that your carb heat system is working is to see if there is some carb air temp rise.

The carb ice detectors will tell you when ice has formed but actual carb air temp may give warning before ice forms. I monitor the carb air temp especially before takeoff and will apply carb heat for a short time before takeoff if the carb temp is 5 degrees C or less.

For my particular engine in cruise I set the carb temp at around 15 degrees C as I find that I can usually lean the engine more, even LOP sometimes.

Fin
9A 0-320
 
I have the Dynon heat probe and a D120. I check the carb temp every time I pull carb heat . Used it today actually. I look at the reading during my run up, then pull the carb heat and quickly see a rise of ten degrees or more . I then know for sure the carb heat system works.
Ron
 
Read one of my recent posts on how to get carby engines LOP.

You might find the temp sensor usefull then.:)
 
carb temp sensor - Yes

I've read too many NTSB reports : "engine failure on takeoff, unknown cause". I imagine that many of those are carb-ice. I live in the NW, where it is wet and cold often. When taxiing out, I monitor the carb temp (installed in the carb throat, just below the butterfly valve, MA-4SPA, 0-320). If it's < 35F or so, I taxi with carb heat applied. Same thing when at low revs in the pattern. When greater than that, I leave carb heat off (less soot in the pipes & plugs). That said, I've had carb-ice only twice, both during runup on perfectly cold, wet NW winter days. Never in the air. Bottom line: it's a data point - I want to know everything the engine can tell me.

- Steven
700+ RV3 hours
(2 more today!)
 
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