Recently, I have developed what sounds to me like some noise from the left side of my engine. I believe it is in the valve train (tap, tap tap). Also on the same side I have two spark plugs that consistently oil foul, sometimes to the point where the cylinders miss fire. The heads are original chevy heads. I would like to figure out what the issue is. If everything on the bottom end is good I would like to install some aftermarket heads and a roller cam with retro-fit roller lifters. Any insite would be greatly appriciated. The other option which I would like to stay away from is a new crate engine. The car does not smoke so I don't think that my rings are bad.