Thanks all for the encouragement to persevere, and for the tips in bolt extraction. Finally got both heads from my 2000 Disco II.
Some tips for would be followers:
Use 5/8 in with 6 point impact socket with 1/2 inch drive instead of a 16mm socket.. Even though it is 16 mm bolt (0.629), a 5/8 in socket (0.625) also fits but with 4/1000 tighter tolerance. I rounded 3 bolt heads with a 16 mm 12 point socket one of which I was able to remove with a 5/8 socket. I would also apply anti-seize compound to the bolts when putting the head back on. Enclosed are pictures of the heads and head bolts. Notice the fractured bolts, the threads are dry compared to the ones that came out intact. Lots of carbon deposits on the heads.
http://i160.photobucket.com/albums/t...7/CIMG0329.jpg
http://i160.photobucket.com/albums/t...7/CIMG0331.jpg
http://i160.photobucket.com/albums/t...7/CIMG0326.jpg

Ed

 

Ed, next time you do this, leave the exhaust manifolds on the heads and remove them from the Y pipe, it is easier.
Did you remove both heads?
When it all goes back together make sure you flush that engine out, it is way to dirty.
Let us know how it goes.
Mike

 

Mike,

Very true. 6 bolts vs. 16. 2 gaskets vs. 4, plus, I don't have to buy new exhaust manifold bolts (it's recommended that you do not reuse the old exhaust manifold bolts). I removed both heads. Surprisingly, the side with the more carbon deposits on the pistons was the side without the problem as indicated by the MIL codes. Haven't checked the valves yet. If I see some significant valve carbon buildup, I'll post it here. I also am considering changing hydraulic lines and hoses since some of them look a little shabby. Yup, I plan to drain the oil and drop the pan at the end of all this.

Ed

 

Link to pictures of exhaust valve from 2000 LR Disco II with 97000 miles: Only the exhaust valves were carbonized this one being the
worst:
http://i160.photobucket.com/albums/t...7/CIMG0337.jpg
http://i160.photobucket.com/albums/t...7/CIMG0336.jpg
Ed.

 

Time for an induction cleaning and a can of B&G's 44K, fix that right up
Mike