Smoke from breathers.

Very nice Dart, one thing I would do is pull the oil dip stick and see if you see or feel air coming out of it, a head casket can leak between #4 and #6 (lets just say) and it will push compression back down in the crank case, I had a friend that had this happen and a tec here in town said a head it cracked.... I looked at a picture real close and told him it could be just a blown head casket, sure enough the head gasket was leaking between 4 and 6.