Catastrophic Failure of the Camshaft Bearings

Some/most of those 340's had crappy oil feed junctions at the mains.
Its 2 holes that intersect and the factory does not bathtub the intersection like the 360's and majority of 318's.. so the end result is a thin web of iron and the equivalent of a half moon opening against a typically misaligned oil hole in the bearings... so its capped by the bearing shell and restricted.