Thanks, Pat... I've only looked at the plugs when I'm changing them in the garage at home. I've read about clicking the engine at the end of the run, even under full power in gear . The impression I got was this was to read the insulator to determine whether timing is too advanced or retarded.

I'll start a new thread on this maybe tonight and we can talk about plug fouling vs. mix, time, etc...

The part I don't get is the black plugs up front and the leaner plugs in the back. One guy at the track with big poncho motor (mine's a BBC) said these GM motors are always leaner in the back cylinders but I just don't get why other than poor atomization of fuel especially with a dual plane intake I would expect the mix to be more uniform. Meanwhile, I'll search CHR as this must have been discussed before...

Thanks again,

Chris