How does this spark plug look like to you?

yellow rose said

Either the plug is too hot or you have too much timing on it. What engine is it? And what plug is it. It certainly isn't lean at idle and a cruise. Can't tell about WOT.

Those picture charts are worthless.

Click to expand...

My assumption was he had a fuel related question by mentioning "jets." I read spark plugs (aircraft...not a big difference) routinely as apart of my inspection process. Not trying to dispute a timing problem, (aircraft engine timing is "set in stone" by the eng. data plate, i.e. 25 deg. TDC means just that) but his spark plug pictured (in relation to fuel) shows to be a "little" on the lean side, "if" his fuel/air mixture is what is causing his "drivability" issue. Just trying to help.