I had the car running well last week. It idles stably (smooth 15inHg in drive at 650rpm), runs cool as mentioned in another post, and has plenty of power. It was grab when downshifting and keep chirping through second until I let off. I was content, but wanted to see how fuel and timing was by looking at the plugs. Turns out they're all over the place as you can see in the pictures (left pic is passenger side and plugs are arranged in order of how they would be in the motor). These are the NGK equivalents of R43 plugs. This was after idling for a bit when I got back in the garage.
4, 6, 1, and 8 are pig rich. 2, 3, and 5 look ok. 5 is a little wet, but ok. 8 looks too lean. The black ones are only black on one side of the valve. I wonder if it's partly due to poor fuel mix, especially with a 9:1 350 with large valve heads.
Any thoughts on what's up with this? Could it be inconsistencies with valve height, compression etc? The exhaust rather loud, but its consistent sounding and I don't hear valve train noises.