Yep, dead sure. Been there, done that. The "5" plug in my R comes out snow white except for a faint orange-tan section from the unleaded fuel deposits. The engine runs so cold I had to put a thermostat in it. The pipe sits at 180*F on idle.
That brown-tan thing means HORSEPOWER. until you hit that region and really learn to tune, there aint no making big horsepower. That little bit of brown gives the spark somewhere to go except through the fuel. Its called "misfire."
Give up your ancient ways and learn how to tune and read spark plugs. Dont take my word for it, learn from the
top fuel world. That "little bit of brown you dont care about" means win or lose, run or explode to them:
http://www.dragstuff.com/techarticle...ark-plugs.html
"Normally aspirated cars should have a light gray or tan hydrocarbon ring or as some call it a "fuel ring" all the way up inside around the third area closest to the point where the porcelain is attached to the metal jacket of the plug. The actual color may depend on type of fuel you use. This fuel ring should appear like a light shadow.
Normally the white area of the porcelain has a chalky appearance. If you see the porcelain take on a shine then it is time to change the plugs because the glass that is in the porcelain has been melted and has glazed the surface. If the car has been running rich (due to lots of idling or incorrect fuel mixture) then it is possible to
glaze the plugs and short them out during a run because of the sudden heating of the plug with the soot on the porcelain."