I'm getting a lot of carbon build up on the plugs, i'm using the 4 electrode type.
after around 6000 miles there is build up. there is also a ring of carbon around the exhaust.
My guess is there is air leaking somewhere, but i don't know where to start looking.
All the plugs have around the same amount of carbon.
Any one else experience this?

 

What brand of gas and octane? Have you replaced your plug wires with 8 mm wires?