[mtdaniel]

I change plugs every year regardless of how few miles. At any rate I contacted NGK for their input. They said with my setup. 488 with ported edelbrocks a xr 288 cam n 10.6:1 comp. The iridium plug BKR6EIX in a 6 heat range is the plug to use. They replaced the NGK V Power 5672 A in a 8 heat range which I had usually used. They felt the 8 heat range was a little on the cold side and recommend a 6. (No nitrous on motor) At any rate the old plugs I pulled seemed to have a decent color to them. I installed the new plugs and drove it 20 miles. Pulled a plug and they were white. I have since went up 3 jet sizes and the plugs are still white. Not sure if I should keep going up on jets. Put a cooler 7 heat range plug in . Or just go back to a new set of my old plug style. The car does seem to run smoother . Any help is appreciated.