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VG33E piston to valve clearance

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  • VG33E piston to valve clearance

    Has anyone ever checked this clearance on their VG? I'm building a new VG33E and I have a couple potential issues. One, the machine shop I used milled the heads .010" and after I decided to do some block work after all, I may end up decking it .003" to take care of the slight twist. This combined .013" is more than the .008" combined spec offered in the FSM. I can't find a thicker head gasket and I'm planning to use early Z31 cams with a little more lift (0.039" more). I want to make sure I'm not going to have a clearance issue.

    I'm not 100% certain what the impact is of the suggested .008" combined block deck and head milling is, but I calculated combustion chamber volume difference from milling the heads and the impact on mechanical valve timing from the combined physical difference in elevation between the camshaft and the crankshaft and both are negligible. I'm guessing the risk of going past the .008" would be piston to valve clearance.

    Anyone ever measured these or know if I'll run into any trouble with this setup?

    Thanks!!

  • #2
    That will bump up compression a bit. I have wondered myself what this would come out like, custom cam wise. The VG33 has piston with recesses cut in while the VG30 does not. I would think piston to valve clearance would be plenty if you are running VG30 cams?
    Straya, +61

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    • #3
      Hey, thanks for the reply. Yeah, good point about the piston difference. I know the VG33 has relief valves, and less aggressive cams compared with the VG30. I forgot there would be even less clearance with a very similar setup on the VG30. I'll have to check the FSM on the VG30. I wonder what their head and block machining limits are posted at. ??

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      • #4
        Assemble head to block and use modeling clay or playdoh on the pistons to verify valve clearances.

        My gut feeling is you will have lots of room to spare.

        1986 300ZX Turbo.....1994.5 B13 Sentra LE.......1985 720 2wd......2014 Juke Nismo RS 6mt pearl white

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        • #5
          Originally posted by NissanEgg View Post
          Assemble head to block and use modeling clay or playdoh on the pistons to verify valve clearances.

          My gut feeling is you will have lots of room to spare.
          Ok, thanks for the reply. I will do that, just to be certain. I'm curious how much clearance there is!

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