Hi! what heat range do you go with? i am @ 5 on my procharged 383. And plugs is all black dusty.. To cold plugs or bad fuel mixture? Procharger recomended NGK 7938 gapped to 29

 

Cold plugs will need a leaner than stoich AFR for idle and part throttle.
they will also need periodic cleaning.
Just sand-blast the tips, then cook the tips for a minute or two with a propane torch to burn all the fuel byproducts and moisture out of the insulators.

If you are running EFI, then make some adjustment to your time-out fueling after start-up, your warm-up enrichment, and make your DFCO more aggressive.

To run leaner than stoich you will have to run Open-Loop.

The above changes will extend the period between cleanings greatly, but you'll always have to clean the plugs periodically.

 

I'm guessing that you are too rich. I'm running Autolite 3923 plugs at .035 gap for 10psi. They are one heat range colder than the ones you are running (NGK 7938 = Autolite 3924). My plugs always look perfect, but it seems like they need replaced about twice a year anyways. From info in the post above, it could be because I don't clean them, but I figure if I'm gonna take the plugs out for any reason, new ones are going back in.