Piston to head clearance??

Discussion in 'Engine Tech' started by jimmymack87gn, Feb 1, 2012.

  1. jimmymack87gn Boost Junkie

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    piston 0.010 out of the hole, will double stacking the stainless shim RJC head gaskets yield enough clearance??
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  3. charlief1 Just another kinky six

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    Assemble the engine without gaskets and put some caly on the top of the piston. Roll it over by hand and see what happens. If the valve contact the piston you shouldn't be able to rotate it that far and you can pull the head to see how far the valve needs to go down.
  4. bison Moderator

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    It will be close but should be ok. The piston rocking will be the
    determining factor. I've run .010 out with a .040 gasket and had it clear. I ran .013 out and I
    could start to see a light shadow on the head. Tight=power and efficiency
  5. jimmymack87gn Boost Junkie

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    not asking about piston to valve clearance...
  6. jimmymack87gn Boost Junkie

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    Thanks!!!
  7. Buickrat Member

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    I would run a .050 head gasket with cast or steel rods, that will give you a .040 quench height. .040 with pistons out of the hole is to tight.
  8. turbofabricator Well-Known Member

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    Order Cometics in the thickness you need.
  9. jimmymack87gn Boost Junkie

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    engine in my car has cometics & have leaked since day 1, building this one for a friend
  10. jimmymack87gn Boost Junkie

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    I guess what I mean to ask if anyone knows what the compressed thickness of 2 rjc stailess gaskets are???
  11. turbofabricator Well-Known Member

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    I spray copper coat on each layer of a Cometic and never have an issue with leakage. I've cracked a cylinder wall and the gasket is still in GREAT shape. To answer your question, though, stacking gaskets is going to double the thickness. If they are .020" then two will equal .040". Maybe slightly more depending on sealer used. Your deck and head surface MUST be smooth when using steel gaskets either MLS or single layer steel ones. Factory machined block and heads will not properly seal with a steel shim type gaket. The RHR finish of the factory machining creates small channels for fluid and compression to leak from.
  12. pacecarta ----------------

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    stock gm were .017 ea . rjc uses 2 stacked per side so .033 , stacking two sets (4 shims) .066 ..same as a GM composition stock gaskets but more expensive , you can get cometics in various heights , .040/.050/ .060

    from rjc site the gasket he has is .033 compressed
    http://www.rjcracing.com/product/head-gasket/
  13. bison Moderator

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    Check the compressed thickness with a feeler gauge after install. I've found stacking gaskets doesn't add up like it should. Usually results in more thickness than anticipated.
  14. jimmymack87gn Boost Junkie

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    Don't know why i didn't think of this, am going to try it this week. I greatly appreciate all the input.


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