My son has a mildly modded 360 in a Dart, and is running a Holley 670 with headers. Compression is stock. Engine has always fouled plugs, and on startup, a deposit of black soot gets on the garage floor. Car has been sitting alot in recent months, due to body work.

My ideas:
1. Go to a hotter plug (not sure what he has in there now, but they are for a stock 318.
2. Adjust carb for a leaner mixture. (Not sure where he has mixture now.)

Also, what is the consensus on ignition timing recs?

Ideas on these 3 points?

He is in Oklahoma, I'm in Mississippi trying to help him out.

Thanks