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