Join Date: Aug 1998
Location: Waldorf Md. USA
This is normal with a lot of the newer blocks. The double roller chains will hit on the block right at the top of the middle oil galley. All you have to do it take a die grinder and grind away the block until it clears. It does not take much. Just did one at the shop Saturday morning. I dont know when GM changed the block castings, but almost everyone we have seen lately needs to be "massaged" You can do it with the engine together if you are careful. Have someone hold a shop vac nozzle right up to the carbide bit while you are grinding. Nothing earthshattering...just part of engine building.
Hope this helps,
Advanced Automotive Machine
1971 Chevelle "Heavy Chevy" original owner