[Dralf1965]

I managed to remove the cylinder head from my RHD S4 last night, and it only took 2.5hrs. I don't think it's been off before, but with the help of the lifting tool it was a breeze. There was little corrosion on the head studs luckily. The engine has done 90,000 miles, and was a little tappity when hot, and would also burn oil on the over run. I am going to take the head to Hamlins machine shop in Bridgwater, and get them to check it over , fit new guides and anything else. Is there any point in going to three angle valve seats? The cylinder bores look really good, the performance was always fine anyway. I did notice that the return pipe from the fuel rail had completely folded and collapsed into itself, this couldn't have helped fuel delivery so will be replaced. The engine and bay is going to get a degrease and cleanup, and the rad will come out for a rebuild/paint, and i will replace the power steering hoses, which are starting to weep. Then i will repaint all the black painted items in the bay, and polish up the ally bits, should look much smarter then. So not much to do!!

 

[spiderserie4]

Is there any point in going to three angle valve seats?

What exactly do you mean here? You mean re-machine the seats? This I would only do if you see they are badly pitted (sometimes a leaking valve will lead to the over-run you speak of) If grinding in doesn't do the job, then yes a minimal remachining is the only thing you can do without fitting new seats. But remember when you remachine the seats the tappet clearance gets tighter, so if they have been machined before you might get into difficulties maintaining the minimum valve clearances (as in another thread here! remember smallest shims available are 1.3mm, and in increments of 0.025mm)

Check the piston liner protrudence in the block is within specs. This is important. (if it isnt, you will have to take these out and insert new lower O seals in the block) But if the head hasnt been off before you should be OK!! Should be 0.01 to 0.06 mm.

Guides and seals is always a good idea. If valves are badly pitted replace these too! No amount of bedding in will correct a badly pitted valve.
Check springs are within tollerances and replace if necessary

And when you get it all back from the machine shop check their work thoroughly! Do the petrol check on the valves to make sure they are 100% tight. Check the valve clearances (better still, give the machine shop the cams so they can set these up for you!...and give them the correct valve clearances for the S4, which are Intake 0.380-0.450mm Intake and 0.430-0.500mm Exhaust, for the Motronic engine)

Oh, and check the chain tensioner is ok-as a matter of course i would replace the spring.