Never seen this before the motor was running for a few minutes at 2000rpm, timing seemed advanced enough, pulled a plug, it was white. I don't know...

 

Sounds like your running way to lean. I know you have a 383, but what cfm are you running, and your compression ratio also???

 

too much advance can cause that too..

Daz

 

White plugs = lean

Retarded timing and crappy fuel can make the situation worse on a run-in.

 

rejetted the carb from 67/73 to 73/76 and the plugs are starting to brown up, and no header glow. Because of the crazy temperatures, I never got to "really" break the cam in for a full 15-20 mins. More like 5 min spurts. but I'll try again, it hasn't been under load yet, so I think I'm OK.