Back in the day, the way we gauged jetting from porcelain color, was to shut down during an extended full throttle run, and THEN pull & examine the plugs.

6 VOLTS/POS. GRD. NW INDIANA

I guess I need some sort of AFR gauge to see if I'm jetted correctly.   I may go back a couple of jet sizes for now.

Could you expand on this statement " I look at the threads for the heat range yours do look to be on the cold side."   Not sure what you are looking at, are you saying it's too rich or lean?

Does this tell you any more?  

I do not use the inner porcelain of the spark plug for fuel mixture adjustments.  Coloring of the porcelain simply takes too long and especially with ethanol laden fuels.  I look at the outer ring where the strap attaches for mixture adjustments.  I do look at the porcelain with a magnifier for signs of detonation and excess oil in the combustion.  I look at the threads for the heat range yours do look to be on the cold side.

Other comments always welcome.

Lorena, Texas (South of Waco)

Look for videos on YouTube where they cut the spark plug so that you can just see the inner insulator.  They say that is the best way to figure out if you're rich or lean.  

If you are using ethanol mixed fuel, then you may need to jet up another 3-4 jet sizes.  Joe-JDC

JDC

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I changed spark plugs last week.  After 150 miles I checked them, they we totally white.  I increased my main jets from 50 to 53.  This is what they looked like after 200 miles with the 53 jets.   I increased the jets to 55.  How long should I wait to see if they are still white, or hopefully tan?   The car is running really well, except for hot water temps when the AC is on and I'm doing 75/80 MPH for 15 minutes