Wow - that looks like a bad idea! I can't quite see the crack but it's reaaallly easy to see the cracks in my block....
I assume the top hat liners' overbore protrudes down beyond those slots.

Can the cylinder bore be oversized to increase displacement beyond 4.2?

 

I should, of course, have mentioned that the later slotted blocks have a wider bridge between the bores as the two liner thicknesses are incorporated into the block, but the slot means there is still not much metal between bore and coolant passage. It is, however, a lot better for the head gasket which lasts a lot longer on these later blocks.

Addendum
Sorry, missed your last post ! The lipped liners are designed to just touch each other or at least be very close, thus covering the crack and giving the gasket fire ring some thing to bite on. I also forgot to say that once the crack appears the bridge strength of the metal between the bores is lost, so it usually sinks a bit thus taking the clamping pressure off the head gasket so failures will occur on a new one after a few thousand miles. How do I know ? Don't ask !!

 

Work on the XJ has been stalled for awhile due to a lack of time, energy and focus. However, I finally moved the car to my shop where the next phase comes into play. In the coming weeks (months?) I expect to:
- pull the engine and transmission
- drop out the rear end carrier
- remove the front crossmember
- mount the body on a dolly
- begin engine teardown

Please excuse the shameless self promotion....