Warped head, skim?

canolman · Apr 21, 2017

I suspect that this head has warped, it's one I cooked last year when i lost all my coolant. To test it I covered the mating surfaces with engineering blue and scraped it off with a straight edge, not that accurate I know but did the trick. I found low points directly above the exhaust ports. Just a rough measurement with a feeler gauge and it looks about .10mm.
If I get this skimmed to avoid altering compression and cam timing could I use a thicker copper head gasket to bring it back to standard?

spanner · Apr 21, 2017

Machine it is the best. It has gone soft near the hot spots; exhaust ports.
You can only try it and see.
There is a guy selling copper head gasket on ebay.

canolman · Apr 22, 2017

There's approximately .05mm between the level of the two casing halves, never leaked 'outward' but would a copper gasket fill this?

ede · Apr 23, 2017

I don't have any personal experiences with copper gaskets, but according to what I read (Given the Choices.. Why would one use a copper head gasket? ? SCE Gaskets) cleanliness is absolutely important. Flatness deviation should not be bigger than 0.002mm. You can also read the thread by Dr_C (http://husaberg.org/mechanical/18816-technical-adventures-dr_c-7.html, starting from page 7) or check out his video post about copper head gaskets (https://www.youtube.com/watch?v=QcYIjbSIwJQ).

I assume the gap is to big since it's about 25x bigger than proper flatness deviation. Since the material doesn't compress I guess there is the risk to damage the head or the cylinder/crankcase when you increase the torque values for the studs when trying to make the gasket seal.

But consider - I didn't try out myself yet.

canolman · Apr 24, 2017

Ok, before I get ahead of myself i need to get the head checked out and skimmed.
The casing halves were machined by JBS to accept their big bearing conversion it seems strange that they wouldn't address the case heights? Unless the halves are from two different engines......
How much would have to be skimmed off before compression and cam timing are radically affected?

bushmechanic · Apr 25, 2017

0.1 won't make much difference unless it's already been done once or twice

canolman · Apr 25, 2017

Cheers bushie,
Just got the head back, I asked for before and after measurements.
6 thou/015mm had to be removed.
I'd like to use the standard head gasket and timing but do you think this is too much?
Many thanks

bushmechanic · Apr 25, 2017

well its a good idea to check everything

compression ratio piston to valve clearance and squish

id machine the cases flat put it together with a gasket then check all the clearances with clay volume with oil etc

then work out what thickness gasket you need

spanner · Apr 26, 2017

Yes copper head gaskets need everything spot on.
The top of the cases tend to distort after a while.
I checked this set of 450 cases on a surface plate and
found it to be "high" in the areas marked.

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I lapped them flat before I bored them out round and
a bit larger.
You would wont to check the cylinder for roundness,
and if it is, check it again in the cases with them done up.
The cases have been known to go out of round.
The copper gaskets are available in quite a few thickness so
regaining the correct height is not a problem.

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