Quote:
Originally Posted by 2SlickNick
Why is half the plug have color? Weird.
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poor a/f mixture distribution inside the combustion chamber. you'll notice the side of the plug facing the intake valve will have more color. that's where the mixture is heaviest.
Poor Flame travel- ignition occurs on the intake side and the flame travels around the plug rather than having the whole chamber burn at once.
lack of intake velocity, not completely filling the chamber. and a little too much advance, plug fires before chamber is full and total compression is reached.
Lots of thinking and some crazy ideas went into this issue. Reshaping chambers to promote improved distribution of the fuel charge and flame travel. Some have tried cutting grooves in the ceiling of the chamber to direct flow. Indexing the plug- using shims so the electrode faces the intake valve when tightened into the head. A real pain to do. The old "splitfire" plugs with the split electrodes made claims of better mileage and performance by creating a wider spark to compensate for poor distribution.
The top of your piston tells the real story. the carbon build up areas are the cold spots, less flame.