I borrowed a really small mirror on a stick and with a mini maglite, checked each piston crown and then the valves in each cylinder.
No dings, no shiny metal on metal bits, so the metallic rattle is a bit if a mystery.
A friend of mine has a theory that the timing was so far out that the inlet valve was still slightly open when it fired and the sound was the valve being slapped closed.
Me? No idea. I did find out
why the belt slipped though.
I found it when I was changing all this stuff.
It was actually this that was the problem.
Well not this one, this is the new one. The old one on the car was the culprit.
It is the belt tensioner stud.
What the problem was, was not that the tensioner was loose on the stud, it wasn't, but the stud was loose in the block.
This allowed the tensioner to loosen when a big persistant rev was applied and the loose belt skipped. It didn't happen before, on the road, because the car has a DR30 3.9:1 ratio diff. 7000rpm in 2nd gear=100+kph so any long bursts= loss of licence.
Only on the track did it get a rev of sufficient length to cause a problem.
By the way, Kev was the 2nd person out in the car, I was first, he just happened to be in the wrong place at the wrong time.
(There you go lad, you've sweated enough

)
So the washup is the engine is back to it's old laggy self with no discernable loss of power, actually it's going harder than ever.
I have to admit though that I'm beginning to really like the transition from no power to everything in the space of 200rpm
Hooks