Part of the reason I love old cars is that you can fix them without having to plug them into a laptop. When something breaks you know it will be something physical that can be repaired.
Recently the Metro has been running mega rich. It has been leaving black, sooty splatters on my Mums car in the morning from the exhaust. I decided I needed to sort it out and planed to buy a Colourtune. I mentioned it to Dad and he told me there was one in the shed (Another advantage to owning old cars. Dad has all the specialist tools already, haha!). I had a look and sure enough, there was a dusty old box sitting on the top shelf with a Colourtune in it.
I love using old tools like this. Essentially the Colourtune is a transparent spark plug which you use to see what colour the flame is inside the cylinder so you can determine if the air/fuel mixture is set right. It’s an extremely simple bit of kit but is worth its weight in gold. If the mixture is too rich, the flame is orange and when it’s spot-on the flame is blue.
So I whipped out plug number 1 and fitted the Colortune. The flame was a deep orange colour which didn’t surprise me at all. The mixture had been so rich the car didn’t even need any choke in the mornings. I backed the mixture screw off a few turns while the engine was running. As the mixture weakened you could see the flame changing colour from orange to blue and the revs slowly getting a bit faster. It got to a point when the revs started falling, so I turned the screw back a quarter turn and that was it, the mixture was set. The car is running spot-on now!
I love old tools!