Roscobbc
Moderator
Thought I'd post these images of the spark plugs as they come out of my engine. They have been in the car for two or three years. I normally change them every two years - not on a mileage basis but because I live in a fairly built-up outer London suburb they are operating a lot of the time on idle and the transition to main jet. Being a fairly 'cammy' engine with a choppy idle the idle mixture on the race spec 950 DP carb does need to be on the rich side and the plugs will ultimately 'soot up'. Primary main jets are fine - these are jetted bang-on so no issues here. You'll see the electrode tips are a mid coffee colour and the carbon build-up lower down.




