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Porsche Crest Mill the heads ?

Enjoying the 1981 930.Did the engine rebuild last winter. Shipped the heads out for rebuild .They said they didn't need resurfaced , but noticing some leakage between head and cylinders . Was wanting to cut .004 in. off the face and call it a day . Was wondering if I could run into any issues .
Old 02-05-2018, 05:49 PM
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Have you rechecked the torque on the heads. This will also show if a stud has pulled out or broken.

Rahl

Edit; Did you replace the original head studs? If so with what?
Old 02-05-2018, 07:18 PM
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All studs are tight .Replaced with Supertech .On the rebuild there were three different types of head studs so who knows how long it ran with broken studs .There are portions of the head face to cylinder that are polished , looks like head movement?
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Higher than stock boost threshold can cause cylinder to head movement....are you running at .8 bar max stock boost, or are you pushing it harder?

Did you "fire ring" the heads during rebuild? Then use the appropriate copper rings & gaskets?

Mark
Old 02-06-2018, 11:16 AM
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Milling 0.004" off the heads is no problem at all.
If you're reusing the cylinders, consider having them ground on the sealing surface to ensure they're truly flat, and that surface is 90deg to the bore.
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Old 02-06-2018, 11:31 AM
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Quote:
Originally Posted by TurboKraft View Post
Milling 0.004" off the heads is no problem at all.
If you're reusing the cylinders, consider having them ground on the sealing surface to ensure they're truly flat, and that surface is 90deg to the bore.
This. Surface the heads AND the cylinders. Only doing the heads is only doing half the job.
Old 02-06-2018, 12:27 PM
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Mark the engine is stock no fire rings. Thanks for the .004 reassurance. Just want to remove the surface fatigued metal. And yes good heads up, will take care of the cylinders.
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Some people also go to the trouble of lapping the head with the matching cylinder.
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Old 02-07-2018, 06:57 AM
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