Originally Posted by 4 Jaw Chuck
That plug looks slightly rich to me, not bad though and might be OK for power if the temps were high that day and you want a jetting that works for colder weather (under 60F).
I don't use rings on the insulator for checking jetting, the fuel today doesn't color them well like they did in the old days. Use the ground electrode instead, the tip should be blue and the carbon on it should be gone almost to the shell. Using that criteria that plug looks rich to me, unless your running race fuel of course.
Drop two sizes and post a pic again.
Thanks for the info! I will post an update after I drop a couple rear jet sizes. I have to order them from summit since I'm missing 78s.
Just curious, when you're looking on the ground strap, how do you defrentiate between fuel and the heat range? I know I can run a 1 step hotter plug and it will take the color past the bend. I'm a newb at spark pug reading so I'm trying to get the technique down. Thanks!