The mysteries of the carburettor will take me pages
and pages to explain, instead, lets explain the two
most frequently used terms when referring to your
carburettor.
Rich refers to the fuel/air mixture, which has more
than the optimum amount of fuel. It is 'rich' in fuel.
Lean, refers to a mixture with insufficient fuel and
therefore excessive oxygen (in the air).
Sounds simple enough. Mixtures which are far too
rich or lean will not permit the engine to operate
properly, so when you hear someone at the track ranting, about either their engine being too rich or lean, they are talking about their mixtures, which allow their engine to run, but also has an effect on it's performance.
A rich mixture will cause your engine to run at a less than top efficiency, but will cause no mechanical damage apart from the occasional fouled spark plug. This simply means that your spark plug has short circuited across the electrodes by unburnt fuel and oil, and, stops sparking.
A lean mixture on the other hand is a bit more dangerous and will also cause your engine to run at a less than optimum performance or worse. The excess oxygen causes the mixture to burn very hot and can cause damage by overheating the piston and breaking down the lubricating film on the bore. This may result in a melted or seized piston.
Advice: Set your carburettor settings to rich to start with, and then lean down to the optimum, rather than the other way. This may save you an engine rebuild!
It takes lots and lots of practice to tune your carby to the exact or correct mixture whilst racing. Even the pro's bugger it up every now and then. There are however, tools in the market place to help even the most advanced drivers' tune their carby's. Such as the 'EasiTune' and now the Alfano Pro+ LV. These tools work by simply displaying a light system on the unit, which basically tells the driver 'green' your mixture is spot on, 'Red', you have buggered it up.
Till next time.
