Hi,
Of the engine blow up?
No. It could have been a stuck exhaust valve that snapped or it could have been the cylinder wall in cyl. nr 4 collapsing into a water channel.
The block had been seriously overbored in the US, original piston size was 82mm. When I got the car it had XK (83mm) high compression +0.040 oversize pistons.
Now it has new XK (83mm) STD pistons together with top hat Mahle steel liners.
As forensic evidence I did find what appears to be a seriously deformed valve dish inside the water channel of the block.
Cheers!
PS. There is a looooong thread about that engine rebuild, this thread is about the steering. 