cylinder head question

[sujitroy]

The heads I sourced have been skimmed so much that the valve head are popping out of the surface. Not only that the head appears to be skimmed at a noticeable angle and I'm 100% sure the that the angle between the heads will be more than 90 degree. I see 1 mm saver shims on ebay. Do you think this along with a thicker head gasket I can save my heads be scrapped? I'd like my machine shop to make it square again. If anyone has a head on the bench, can you measure the distance between the front bolt hole and bottom of cylinder head. Here's mine. This will give me a crude measurement of how much has been removed


Regards, Sujit

[Phil S]

I would have thought measuring from the cam cover mating face would be safer as that face is a more suitable datum

[sunnystag]

So by my reconing. I will let others correct. don't bother with the 0.5mm saver shims. get the 1mm. then the extra thick gaskets ( thats the BGA ones) add when compressed about 0.6mm over std gasket. So with both u can add 1.6mm if that helps. also I read that had 2mm savers in Australia if u need more...don't know if they're still available.

[StagJonno]

This is info I was given by a friend during my recent head job. Skimming Heads - Critical Dimensions.docx .

[flying farmer]

Measure from the camshaft bore as in the document above. The thickness of the flange where the front cover fits is very random as it is a cast part not a machined one.

Tony Hart once told me that they could be skimmed until the cutter hits the inlet valve seat and still be useable with saver shims

[sunnystag]

Hi Sujit
I tried the ball bearing and micromenter measuring as per Jonnos's technical reprints, found if hard to get a reliable measurement but - the fact your inlet valves are pertruding the head face means that they are skimmed beyond triumph's spec anyway.
But they are often still usable,
indeed still usable right up up to the skim taking the head face to touching the value seats ( as long as you use the saver shims). It is key to have a 40 thou gap to pistons. search this forum or google for flying farmers comments to how to measure - i have a noted this somewhere if you need it. You do need to do an insitu measure head on block with the value overlap as when a piston is at TDC not at power stroke (valves shut) but TDC between exhaust and inlet where there is a tiny value overlap. needs to be insitu measurement of gap with bluetac or the like, as some cars have had skimmed blocks whic h makes pistons higher, also mk1 or mk2 pision will make a difference. so when that tight measuring head alone is not enough. Then just make sure your shims and gasket make enough gap.

For me the saver shims brought the cam timing back and let me fit the inlet manifold with the better payen inlet manifold gaskets rather than thin inlet manifold gaskets as well of course as hopefull reducing compresion back to spec.

[sujitroy]

Thanks for all this info. What I'm more concerned with is that if the face should have been machine perpendicular to the exhaust manifold attachment points, I can clearly see that this is not the case.

Sujit

[StagJonno]

Can't help there, Sujit. I have a spare pair that have been overskimmed, but putting a square on these wouldn't be conclusive, even though they were reconditioned by a (general) engine specialist..