i recently put a rebuilt 327 in my car. a lot of black powdery substance comes out the tail pipes everytime i start the car or rev the engine. i also am losing about a quart of oil every 1,000 miles or so. i've put between 2-3k miles on it so far. there is also a little oil on the plugs when i pull them out. can anyone tell me what's going on here? should i take the engine back? it runs really good, but these are things i wouldn't expect from a fresh engine. then again, i'm pretty green at this.