A buddy of mine had a strange noise. He had just put a new engine in his 34' Chevy. We had gone to the street rod nationals in Bakersfield and he trailered the rod home. He lifted the car, search underneath for anything loose. Tried replacing the starter. Then his son noticed a gap between the block and bellhousing. It was only on the starter side. Tightened the bellhousing bolts and everything was fine.