Yeah, I'm rebuilding a 350 small block Buick engine and it has a hole on each side of the cam shaft. I'm wondering if these holes should be plugged or open. Thanks for your time!
unless you have an extremely late production 1967 model year car that got outfitted with a 1968 engine ( 1968 is the first year of the 350ci ), i'm not sure that could have even happened.
a Bu 350 will have valve covers that have 6 bolts holding them on, a 300ci or 340ci will have 4 bolt valve covers.
regardless, a 1960s Buick will oil the rockers by weeping from the rocker shaft and there will be a special oil feed hole between the deck of the block and the head which will have to be kept clear of the head gasket in order to allow oil to get to the rocker shaft.
in 1970 or 71, Buick changed to the 'Chevy style' pushrod oiling for the rockers, so those oil passages are no longer used in the newer engines.