Take at look at these photos of a built engine that failed after 90 miles.

[sujitroy]

I bought an engine off a fellow Stag owner here in USA. On its maiden voyage home from the shop, the engine died. The previous owner partially stripped the engine. A valve broke and pierced a hole in a piston. Here are some photos.
Regarding the head, is it repairable. The area around the valve seal has been crushed.

[new to this]

Id say the head is repairable, but machine cost are high,lucky its only the one area to be rebuilt, whats the hole in the cam cover for ?

Dave

[flying farmer]

The head can probably be welded, but how much has it been skimmed? The inlet valve in the next cylinder looks to be hanging over the gasket face of the head which suggests it has been skimmed right down to the valve inserts.
Might just be an optical illusion though.

I imagine someone once fitted a PCV valve to that hole in the cam cover. Was the engine fitted with something other than the original Strombergs at some point?

That chain guide looks plain nasty, the rebuild was obviously a bodge job where they refitted a worn guide or hopelessly overtightened the timing chains (or both) for that amount of wear to occur in 90 miles.

Why did the valve break? Did the head snap off or was it failure of the collets on the valve cap?

[sujitroy]

No clue what that hole, is but Neil has an explanation.
I feel that the heads were over skimmed. I haven't done a deep investigation, but it appears the valve heads are popping out beyond the face. The valve head snapped. On the intact bank, there are indentations of the valves in the pistons. Let me ask the previous owner what carbs he had.

Sujit

[DZP]

That looks like damage caused by running an engine with no oil/no oil pressure.
I would check the oil pump before running that engine again.
Den

[sujitroy]

The cylinders look good. This engine is going nowhere for sometime. I do have a rolling shell for it to go in, but I need to iron out the issues with Stag no.2.
Sujit