Spark plug timing marks

j par said
For some visual inspiration to the thread I went ahead and pulled my number two plug. As you can see I run a cold plug. The car was probably running about 190° the whole time, give or take. 11 to 1 compression. Timing, initial 22-24 and all in at 35-36. Two parts 92 non-ethanol one part 110 race fuel. The plugs have been in for a while and the most recent drove to the track took some passes took the freeway and a recent ride to a friend's house. I've been seeing a lot of 13 in my AF gage. Some 12 at wide open throttle and some 14 at idle, but don't quote me because it moves a lot. ..View attachment 1715344846 looks a little dark to me...
View attachment 1715344849 View attachment 1715344850

Look at the rolled edges. That is too hot, and you are cooling the plug with fuel. You need to get a cooler plug in there and then start taking fuel out.

It's defiantly fat at idle and probably cruise. With the shell on its hard to to see WOT but I'm betting it's fat there too.

Always watch the sharp edges. When they start getting round you are too hot.

Edit: I forgot to mention you are showing heat 3 threads down on the shell. YIKES. That's plenty plenty hot. I don't like to go past 1 thread on a champion, or two threads on an NGK.