Quote Originally Posted by new 32 roadster
The road draft tube hole is about 1 1/4" and on top of the block just behind the distributer. This hole is about 1/2" on the LH head surface of the block, at the upper rt corner as you look at the head. It was mostly covered by the head but there is no corresponding hole in the head. I've been told it is an oil galley passage that should be plugged, but don't ever recall seeing it in other blocks.
far as i know all sbc has that oil gallery hole in them, but you you don't have a reason to know it until some machine shop leaves it out after they clean the motor. i thought most had threads in them, but if not some type of freeze plug should work.