Just to ensure we are on the same page, im looking at cylinder head temperature (CHT).

What is the benefit of EGT? Does knowing that help determine timing advance?

Regarding cht and my K type sensor, I have ordered one of these.

https://www.ebay.co.uk/itm/AD8495-Armz- ... ect=mobile

Both use k type thermocouples.

My understanding egt shows temp change more rapidly as the gas flows past the sensor, with cht the head+ plug there a delay in the temp change.

I guess cht will be lower than egt at the same point in time.

Amplifier is ok so long as it interfaces its the speeduio ok

Yeah, I only really want it to know if the heads are running cold. Not easy to fit a muff to the Shed.

I do have my concerns regarding it being compatible with speedy, as I suspect it may put out a digital signal, and speedy expects analogue.

We shall see

@AD8495 Armz Thermal K-Type Thermocouple Amplifier Analog Output Precision M


analogue 0-5 volts

From Adafruit site
DESCRIPTION
Thermocouples are very sensitive, requiring a good amplifier with a cold-compensation reference. We have a couple digital thermocouple amplifiers in the shop already from Maxim. Now we're happy to introduce an excellent analog-output amplifier. This is a very simple sensor to use, and if your microcontroller has analog input capability, you'll be ready to go really fast!

The AD8495 K-type thermocouple amplifier from Analog Devices is so easy to use, we documented the whole thing on the back of the tiny PCB. Power the board with 3-18VDC and measure the output voltage on the OUT pin. You can easily convert the voltage to temperature with the following equation: Temperature = (Vout - 1.25) / 0.005 V. So for example, if the voltage is 1.5VDC, the temperature is (1.5 - 1.25) / 0.005 = 50°C

Each order comes with a 2 pin terminal block (for connecting to the thermocouple), a fully assembled PCB with the AD8495 + TLVH431 1.25V precision voltage reference, and pin header (to plug into any breadboard or perfboard). Goes great with our 1m K-type thermocouple (not included). Not for use with any other kind of thermocouple, K type only!

Works with any K type thermocouple
Will not work with any other kind of thermocouple other than K type
Easy to use analog output
Temp range with 5V power: -250°C to +750°C output (0 to 5VDC) as long as the thermocouple can handle that range
Temp range with 3.3V power: -250°C to +410°C output (0 to 3.3VDC) as long as the thermocouple can handle that range
Note: The terminal blocks included with your product may be blue or black.

Wow, thanks Pete

That appears simple enough, even for me.

Sensor has arrived, and looks suitably robust.

I had an under plug tc, was a very tight fit over the spark plug, also routing the cable was tricky.

P1020371 by Robndaisy, on Flickr

I know Rob, but you just can't the same quality of fertiliser bags these day.

I'm thinking some ply. I can hear Wickes calling me.

A spark plug fits well enough into the sensor ring, and having compared the outer diameter of the ring to a penny, it appears to be an identical diameter. A penny fits nicely into the indent where the spark plug hole is. The only issue is the way the wires attach to the ring. The ferrule wont clear the indented hole.

Im wondering if bending it will dsmage it.

Photo would help