I have now 400 miles on the new motor as well as these new AC Delco plugs. The color of them is a rust brown or light brown.



Does this look normal, I am thinking the A/F ratio is a tad on the lean side from watching the beahvior of the O2 sensor voltage readings compared to my previous motor.

Thoughts?

 

If I'm not mistaken, that reddish color is from fuel additives.

Tough to say beyond that.

 

That's what I would guess too.

 

The insulators were still very white at 300 miles. I also ran some Torko in my last tank of gas, that may be what turned things brown. The engine runs good and stronk with some mild high RPM KR.


Here is why I Think I am running lean.

The O2 MV readings when bouncing do not get into the 800's or higher on my Scanmaster, the old motor reached 900 MV routinely.

WOT O2 MV is low to mid 800's or so.

I think I am getting some very slight knock at high RPM's. Still might be false.