l was under the impression that XK8 pistons were supposed to be smooth. l cleaned up the piston in the offending cylinder (dropped valve seat) on my 1999. At close inspection the 'dings' in the piston crown are incredibly uniform.

Are they supposed to be there?

 

Short answer. No.
If not for the couple of nicks on the edge, you could have got away with it.
Lots of work from where you are now, which by no means is easy. Sorry, which I was there to help.

 

l read your post had a very good look and well, i believe you are wrong, at least in the work front, and after close examination i think completely, heres why;

Heres another pic, as you can see from the carbon been like that for a very long time (at least 50k kms, i know this due to ownership history)
ive run feeler gauges round several of the pistons there is no change around those areas
There is zero contact on any of the valves
Here is another picture, look at it closely, that is not impact damage, that is a machined surface over a casting or forging, look very closely at the top most part, how it curves back up, thats machined, the chances of that being impact damage exactly the same x 32 hits, i dont buy it. Pay very close attention to the machining marks, there is no way that that is a edge caused by impact

 

lf i get really bored, which i will , waiting for parts i will clean them all and take more pics.

 

Another short answer. Yes they are correct.
Nothing to worry about.


Edit: Markel posted while I was typing.
And yes you should clean them all.

 

Thanks for the conformation Stumpy, glad thats cleared up, ive read quite a few posts where that is cited as damage.

 

There's clearly been some piston/valve contact in your first pic. It doesn't appear to be significant.
The reliefs are part of the castings. I can't find any pics of xk8 pistons that have these indents?

 

OK, so not ever seeing one like that and then seeing all were the same, I stand corrected and clean them up and don't over do it near the edges of the piston. I know, sounds crazy, just the way I learned it from the old guys in England when we did , I believe it was called decoke, been a while (60 years)

 

All pistons have these stampings.

 

What model year?