bizarre spark plug appearance

[flibuoy]

On third set of plugs in a row trying to diagnosis running problem...all correct for LT1/all different manufacturers/gaps experimented with and caused no change. All eight, on all tries, are showing exactly the same results

 

I don't want to give symptoms...just appearance of plugs after just few minutes installed...to keep from influencing your opinions

 

Plug stays clean..as new.. on one side of tip....rich soot on other half. Not half tip to bottom/bottom to tip...but half as in left/right sides. Transition from white to fuzzy black is not gradual, but almost a clear straight line.

 

I have read every article I could find on plugs...not even a close match to this appearance.

 

Ideas?

[Tim240z]

Do you know which side (of the electrode) is facing which valve (intake or exhaust)?

[dr_hunt]

your getting a piss poor burn in the cylinders. Being all 8 plugs indicates to me that it's a plug heat range problem or weak ignition problem (coil, cap, rotor, wires) What compression are you running? Cam? When you say running, is that at idle, part throttle, or full throttle? When you say white, do you mean white as in when they were installed or a brighter white or off white?

 

Typically if you see carbon deposits, especially fuzzy type, it means that the plug is too cold, or if it's hard flaky type, could be oil in the combustion chamber from somewhere. The normal appearance on one side is probably due to the intake charge "washing it off". To read a plug you should run it at WOT under load, put it in neutral and kill it, then pull the plugs and read as plugs heat up the higher the rev's which burns off the carbon deposits. That'll give you a more accurate read on the plugs.

 

Need more info to make a judgement call.

[mark]

how old is the optispark. These are usually the culprit on ignition related problems on this engine.