360 LA installing Promaxx Aluminum heads

I also agree with rat Bastard but still advise a 1 step richer mixture to see what happens as well as the OP said the 02’s may not be calibrated. I mentioned looking down into the plug to see what’s going on. I also think the porcelain is very white. My disclaimer, I never worked with NGK’s.

I figured the richer change could/would show on the plug and the worst case scenario would be to go back to the last step. Such is the way of tuning and many other things about cars.

Hysteric said

You need to wrap the plug in the palm of your hand. Cant tell what colour that is on the ground strap but the porcelain looks very white then that tells you its lean.

Tune to the colour of your plugs not an AFR number. Go up a jet size and see what it looks like then.

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Agreed. The AF ratio via the 02 is a great way to start the process and get you there quickly. It is not the end all. Also hence why I asked if there is a drag track.

IMO, he could just leave it alone and it’ll be good. If he can get great, even better. Considering it’s summer time, when I’m tuning up a ride, if it is a slight off on the rich side, winter will take care of the rest with more cold dense air.