Air fuel ratio question

[randy wilson]

Originally Posted by west coast

Hey Bobby i just use the # as reference and move your target richer or leaner and go off the time slip at what it likes. I tell people how lean i run my car and cant believe i don't have holes in the pistons. ever sensor is different.

I agree with your theory. However lately, like the last 12 years, all 3 engines we ran locally are 3 size jets larger then when just off the dyno. Plugs look almost black, but cars are quicker. One size bigger, we slow down, one size smaller, we slow down. Looks way rich, but quicker by enough to warrant the change.