So putting the horror stories of sheared studs and jammed heads aside I went about removing mine; and whilst I was at it I also removed the sump.
Over the period I have asked many questions from you so thought it might be useful to someone if I shared a few observations.
I have fairly basic tools, a cramped workshop and no pit nor lift. I sat the car raised on sleepers which gave be just enough headroom to access sump.
In total I spent about 2K which included £600 of machining; skim, new valves and inlet guides, recut seats, cleaning. (B&E Randall, Norfolk who were excellent and good value) Rest of the 2K was gaskets chrome nuts, shims, seals, amazing how it adds up!
Some observations:
The heads wouldn't budge so I bought a head lifting tool which made the job a doddle (cost £250 and sold on for £150)
I would advise removing the electronic dizzy as I managed to snap off the vacuum when manhandling the heads.On the side with the steering shaft the exhaust manifolds foul on it when trying to lift out so the exhaust manifold needs to be loosened to allow wriggle room. Not easy access.
I drained coolant from around liners and removed vast quantities of gritty debris esp from around cyls 5&6. My cooling must have been severely compromised. Someone told me that it was sand left from the casting process???
On turning the engine over 5 of the liners popped up but it was easy to clean and refit with smear of Hylomar to shoulders. (correct...I didn't listen to the manual in securing the liners first)
I noticed Bank A & B were 5deg out of sync but was an easy job to adjust on splined gear. Also the crankshaft pulley timing plate was 4deg out. Maybe this was the cause of difference in compression between banks?
The heads needed new exhaust guides and all of the guide seals were perished.
The bores were in spec and still showed some honing marks but were polished and ring gaps were too large. I therefore rehoned using dongle type drill attachment which worked very well. I used a rag stretched over old ring set in bottom of bores to prevent abrasive particles from dropping onto crank.
I dropped the sump and found 15mm thick sludge sitting in pan. No wonder that when I did oil change the new oil would immediately turn black! I also changed big end shell as they are cheap and one had bad score on it. The crank pins were unworn.
I found all 5 or so rings in pump feed pipes and pressure relief valve to be somewhat perished.
The engine is now up and running with compression at 140psi before new rings have bedded in.!
All very expensive, time consuming but in the end worthwhile! I never realised how many cylinders a V12
had
Best
David