J-6;
The "Y block" rockers always had problems getting oil. The oil feed (hole) was offset between the block/head to reduce volume. In time it became restricted (sludge) as the opening was just the height of the compressed head gasket.
Some of the later truck heads had a 'relief' in them there.
Sometimes the cam bearing (feed) would wipe over the hole and block the oil flow too.
Happy trails to all.
