360 LA installing Promaxx Aluminum heads

74Scooter said

Slow day.. spent the morning cleaning up the garage. You know how it gets after a major operation. Anyway I did get around to pulling a plug, this is #1.
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If I had to venture a guess that black smut is leftover from when it was running much fatter.

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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.