Hi guys!
I came across this device ( in my friends basement ), it seems that not so long ago it was still used in the east (made in russia). It basically a glass spark plug - You use colour code to adjust the carb. see for Yourselves.

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Just bought my first MATRA, any materials and data

welcome and appreciated

i know this set as "colortune" spark plug - existing with 1 or even 4 spark plugs.
i think its a good way to tune the carburetors - but in case of bagheera with 2 carbs 2 or 4 plugs are necessary.