While looking at my distributor and the vac advance clamp I noticed that about 3/8" to 1/2" gap between the top of the clamp and a sholder on the distributer shaft.Is this normal or is my distributor not seated into the oil pump? I have been driving it that way for about 2000 miles.Oil pressure is good at first startup and drive,but at highway speeds only about 5-6 lbs.