Ok.. I know something isn't quite right... My plugs are whitish so that would be lean right? at WOT I blow some black smoke in the 5000-5500 rpm range... engine is an '85 L69 with K&N, pulleys, edebrock performer intake, and roller rockers... Timing is at 7* BTDC which is down from the 9* I was running but doesn't help.. call also backfires sometimes when I shut it off... What do I need to do?

Thanks