Cilinder head question

[richard230sl]

I am currently replacing the headgasket of my 280 m130 engine
The head was warped and  it was milled within the 84 mm head height
Unfortunately I did not find a party that could heat straighten it and was to late Reading on this forum that this was the preffered way of straightening it. (Sorry.....)

http://HTTP://www.sl113.org/forums/index.php?topic=1113.msg5715#msg5715

Due to the fact that the milling was quite severe (0.7mm at Some places)  I am thinking of the  advise that I read in another post about a warped head on this forum about compensating compression after milling a warped head. Can anybody advise me how often  this is necessary? (Is it rare to cause problems with these amounts of material removed? (In my case still within the 84 mm)
And if the 4 outer combustion chambers in the head have to be enlarged (the 2 in the middle left alone) :
How should that be done in order to not influence the flow of the gasses too
much?

Any pictures of this job or advise of where and how to remove the material exactly would be very helpful.
Also tips of determining the amount of material are welcome (could i measure the remaining height of the head above each  cylinder and then calculate the amount to be removed at that specific combustion chamber? (Any tricks in avoiding measuring volume with a fluid ?)
Am I making it too complicated and should I just try installing the head without compression compensation and see how it runs as a first step and worry about problems after that?
Fortunately the camshaft is turning very light again after I shimmed the two outer gearing columns
Valve guides and valves will be replaced for new ones. New exhaust seats will be placed.
I will check if the chain spanner will still be able to span the chain with the lower head

Do I need to measure valve vs piston clearance at 5 degrees when still being  in the 84-85 mm range , or should this be fine in that case
Any advise in this stage of how to make this not unnecessary complicated but avoid making mistakes is welcome!
Thanks for all the extra work and mistakes you all save(d) me.

Richard230sl
(Have been a member of this terrific forum since a lot of years, dont know why I had to register again and appear to be new today)

[ja17]

Hello Richard,
If you milled .85 mm you should be ok. There will be slightly higher compression reading on the cylinders toward the ends. But the difference should not exceed 10-15%.  A high performance (racing shop) can measure the volume of each cylinder by filling each combustion chamber in the head with fluid, and then measuring each quantity of fluid in each cylinder. Some head material is then removed from the combustion chambers which have less volume, so that all become equal.  This should only be needed in severe cases.

[Aaron h]

Be sure to also check and/or re-flatten the top of the head, too, or the camshaft bearings could seize to the camshaft journals, the camshaft could break in two, and the valve cover gasket will leak indefinitely.  Alternatively, you can shim the camshaft bearings if you know what the height difference is between the middle and the end, but I don't recommend doing that, especially since the valve cover gasket will still leak. 

[Cees Klumper]

I believe Dan has also recommended flattening the top or adding shims to the cam bearing towers for the reasons Aaron mentions. But I suppose that inevitibly further reduces the thickness of the head. Which leads to the question of where Richard you measured the head thickness - at the ends or in the middle?

P.s. are you the Richard who is on the 42 anniversary poster?

[richard230sl]

Thanks all for your replies!
(and please do not hesitate to add new advices after reading my questions)

Since the camshaft is allready turning perfectly light after I have shimmed it, I will leave the upper part of the head alone and will find a solution for sealing the valve cover. (thanks for the tip Aaron)
Following Joe Alexanders advise (thanks J.A.) I will install the head without further milling and will measure compression after installation.


@Cees: Thanks for your reply;
I measured the head thickness on several places. All well  over 84mm. (thickness in the middle is higher then on the ends)
Sorry : I am not the Richard on the 42 anniversary poster.

I will keep you updated about the progress