I was discussing with a work mate about the colour of the spark plugs indicating if Im running rich (black and sooty) or lean (white). He commented that with unleaded fuel you wont see a clour since there is no lead in the fuel. Is this correct ?. I know my plugs are still like new so I am starting to think this is reasonably true. Anyone able to give me some more info about this. Derek
Not correct. Leaded fuel used to leave a white deposit in the end of a tailpipe. Looking at your sig, if you haven't upped your jetting and backed your screws out from stock, you are probably running lean.
The best description I can give of the proper tip color is pale brown, not unlike the color of Nestles Cocoa (or whatever hot chocolate drink you have down under). That lead coloring the tips is a bunch of hooey.
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You will get some coloured deposits, just not as much as with real petrol. You may have to use a torch (flashlight) and look deep into the plug, as the deposits will be thickest near where the ceramic bit meets the metal shell.
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