Hi Barry,

Thanks for your reply.

The valve seats which had sunk were numbers 11 and 12. The valve seat in number 10 was also showing some signs of discolouration, so I have had the seats in numbers 9, 10, 11, and 12 replaced.

When I ran the engine with all of the manifolds connected, it ran OK, and there was no indication that anything was wrong. It was only when running the engine without the manifold on that I saw anything wrong.

I suppose there was a clue there - the inlet ports for 11 and 12 were sooted up rather than being just oily like all the others - as mine is a naturally aspirated 606, there are connections between the cranckase ventialtion system and each runner of the manifold, so I would expect to see some oil in each port. I'm going to check that this isn't blocked up for ports 11 and 12, because perhaps the small amount of blowby oil is enough to lubricate these valves and seats?

Thanks for your views about the injection pump timing - having read your posts on the subject, I'm really impressed with the work and the investigations you did.

When you suggest that timing using the correct tool is the way to go, which tool do you mean - sorry, I don't have any real MB experience or knowledge.

Cheers