Morat wrote:

In a perfect world I'd pull the engine, install top hat liners and use unicorn lard to lubricate a set of brand new ARP studs but sadly I'm not in that world yet!
If the driver's side goes, that'll get done on its own too. The engine first started a very slight ticking years ago - in fact Marty noticed it when we (he) did the Heater Matrix. If that was the start of this issue then it took a looong time before it finally blew out the rest of the HG.

I had ticking noise for years on my P38 which was always put down to a tappet but perhaps it was an indication that my head gasket was failing.

No way Nigel. Your tapping was definitely valve gear, a cam follower or rocker arm. If it was the head gasket it would have blown completely years ago.

Gilbertd wrote:

No way Nigel. Your tapping was definitely valve gear, a cam follower or rocker arm. If it was the head gasket it would have blown completely years ago.

I wasn't being entirely serious😀

When I did my 4.0 project rebuild, I did a simple mod to the exhaust manifolds. enter link description here

Now it's possible to undo the downpipe studs, and remove the heads complete with the manifolds !! Then heatshields, etc can be done on the bench.

While it's apart check & replace core plugs. They could well be corroded & potential leak point.