So I've been looking for any sort of CHT temp for my type 4 for a while, but resented to spend £43.50 on what is a cheap and possibly highly incorrect unit. So after a bit of digging I've bought the k type thermocupler 5m for £7.20 and a CHT guage at £5.32 for a bit if an experiment to see how correct or incorrect these things are. Ratwell has a good write up http://www.ratwell.com/technical/VDOGauges.html#cht The basics of it being depending on the length of between the cold and hot junction of the thermocoupler and position will could through the readings off, and it's initial calibration temp. So after my little purchases tonight, once they arrive I will do a little investigation on temps and differences as best as I can and will follow up in this thread to see if even worth the £12 odd pound I spent. To be honest even if it's incorrect but I can record the error % I will probbbaly install it in the van depending on my findings. Sent from my Pixel 3 XL using Tapatalk
I think you will find it pretty accurate. The chips they are based on work well. The fun is in extending the thermocouple wire over 5 metres to the front- you ideally need proper type K thermocouple wire. Otherwise the temperature you read at the front will partly depend on the temperature at each wire join as well as the cylinder head temperature. With the probe and converter chip I use there is also a problem that if the probe wiring touches the engine block then it reads zero. This also means metal braided stainless probes can not touch ...
If your thermocouple is k type and the compensating cable you are using is also k type then the reading will not differ by too much, certainly not by a huge amount. If you use n type cable on a k type thermocouple then you will get errounous readings, by up to 100'C in certain instances. Don't forget to set the readout to k type too (unless its auto detecting). We use both n and k type thermocouples and have to have readings with an accuracy of 10 degrees in 1000'C and by using the correct compensating cable, we can get to 5 degree errors in 1000'C.
Have a look here for some more information: https://www.omega.co.uk/temperature/ Omega are owned by our parent company Spectris PLC, the equipment they supply is good quality
i think its the same company but 5meter cable and sensors can be bought https://www.mainline-sensors.co.uk/collections/sensor-cables
I'd looked at fitting a CHT a while ago....Zed recommended using one designed for 2CV racing engines...remember him....told you it was a while ago !
Added the CHT today (far right) works as expected and the 5m K terminal I got was more than long enough. For now though I have only placed it over spark plug 3. Haven't looked Into placing it under just yet as not sure if it would effect the spark plug gap.
Apologies not the gap. But it would raise the spark plug the thickness of the ring, out of the cylinder head unless if there is a recess for it.
It's being a bit temperamental but I think that was due to a loose connection on the sender which I've hopefully just fixed. As it was reading 140 on way to Stanford hall.
The ring replaces the sealing washer; the plug remains at the same depth. It’ll tell you nothing worthwhile just resting on top of the plug.
That's what I thought, just didn't want to go ahead untill I verified. So removed spark plug washer and replace with the thetmocoupler. It's a type 4 motor.
It depends on what heads you have. You might have to make a groove down beside the plug for the wire. I’ll see if I can find a pic.
