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Discussion Starter · #1 ·
I'm having the head gasket changed on the m5 and the mechanic offered to skim the head more than .030 for some extra torque. In addition to the head gasket, he'll will most likely replace the valve seats. I figured I'd check with the board first and see what you guys have to say. Any insight? if i do it, should there be anything in addition to this?
 

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BMW specify that these heads should not be skimmed .

I therefore wouldn't advise it and would be interested to know what spec his headwork would be machined to and what head gasket would be used ?
 

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Discussion Starter · #3 ·
BMW specify that these heads should not be skimmed .

I therefore wouldn't advise it and would be interested to know what spec his headwork would be machined to and what head gasket would be used ?
I thought you posted in some thread that you had skimmed your head, and a year later it is still running strong. What if i use a VAC MLS head gasket???
 

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I thought you posted in some thread that you had skimmed your head, and a year later it is still running strong. What if i use a VAC MLS head gasket???

We HAD to skim the head to get it back level and then used a bespoke VAC mls head gasket to bring back to stock tolerances .

This appears to be a different proposition to what your mechanic is suggesting , which would be to skim the head to increase compression !

D
 

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Discussion Starter · #5 ·
well, if i don't skim it, will i still be able to use an MLS head gasket? also, any suggestions as to what parts to refresh when doing the gasket, besides the stem seats?
 

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IIRC the tolerances are so minimal there is not enough meat to skim the head without the valves collecting the piston crowns, remember BMW spent millions creating these engines and they were highly engineered so why would we want raise compression on such a finely tuned engine?

Are You trying to gain more power? Has there been a problem that you need to skim the head?
 

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My head HAD to be skimmed to get it flat again.
I couldnt get an oversize head gasket, so we machined the "eyebrows" in the pistons just a little to make sure of the clearance.
Unfortunately you have to take the pistons out for that exersize. i Also inserted a shim behind the piston of the s50b32 timing chain tensioner, since the chain is now effectively too long for the skimmed head/engine assembly.
Car did 11000km so far and never experienced any issues.
 

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Discussion Starter · #8 ·
nothing is wrong with the head now. when it goes into the shop, ill get some pictures of the condition of the head and we will go from there. Maybe I wont skim it at all if everyone says Its a bad idea.
 
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