Installed a new set of NGK R5671-7 plugs in the 468 blower car, warmed her up and proceeded to lay down a 100+ mph pass on the street.

Pulled the plugs to find the blue line just about at the bend of the electrode (seems ok).

There's a little, ones of specs, carbon on the porcelin. That was on 93 Amaco pump gas and 28 degrees timing.

There was a little light gray on the porcelin, but almost no color on the base ring (just a little light gray but mostly the shinny silver of the plug it's self).

Seems like I need to add some jet, but how many?

I run two 750 vs.