Help with Head and Deck Height Measurements?

Discussion in 'Engine Modifications (Members Only)' started by cribbj, Feb 10, 2010.

  1. cribbj

    cribbj "Supra" Moderator Staff Member

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    We're trying to get some data on how much "meat" stock heads have on them before builders start shaving them.

    If anyone can assist with this, it would be a big help. Refer to the photo below and see where a height measurement can be taken. This is the exhaust port side of the motor, and for the right hand head, this point will be near the front of the head, just in back of the #2 exhaust port. For the left hand head, this point will be at the rear, just in front of the #7 exhaust port.

    I chose this particular point to measure because:
    1) you can get to it, even on an assembled engine, and
    2) the head gaskets don't poke out and interfere with the measurement and
    3) the surfaces are flat

    I have three early 1UZ heads here that I measured several times with a digital caliper (my mike won't open up this big) and got these results:

    64.42mm on a "junk" head, which I think is unmodified (hope somebody else can confirm?)

    64.17mm on the left hand head on my #1 motor (this head has been shaved several times)

    63.84mm on the right hand head on my #1 motor (also shaved several times)

    I'd also be curious to see what 2UZ heads measure, and if anyone has 1UZ or 3UZ VVTi heads, those dimensions are welcome too.

    We're also going to try to get deck heights for these motors, or at least a measurement relative to the deck height that someone can take on an assembled motor to see how much metal has been taken off the deck. If anyone has a headless motor and wants to assist with this, much appreciated.

    Thanks in advance!
     

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    Last edited: Feb 10, 2010
  2. Sudsy

    Sudsy Member

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    Is that a cast surface you are measuring off. Be better to measure to maybe one of the bolt holes to head face or tappet cover face to head face or cam bearing to head face for a more accurate measurment.
     
  3. ash

    ash New Member

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    Any shaving of the head changed valve timing
    On r&d , the increased compression and put intake ans exhaust valve timing not where I wanted it.
    Head deck thickness..... It was ok to .020 for. Boosted applications.
    Gasket got dodgy after that for 40 + psi
     
  4. krayn

    krayn Member

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    I have a pair of pre and post 95 heads in bits at the moment, and also have a pre 95 head cut up in slices to check port thickness. The pre and post 95 heads have a slight different intake port design and have different valve springs. As far as i can tell the compression ratios differed by the top of piston. The combustion ports seem to be the same. Let me know where you want it measured. Cheers kris
     
  5. cribbj

    cribbj "Supra" Moderator Staff Member

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    The intent of this exercise was to be able to quickly identify how much shaving had been done on a block or head(s), so a potential buyer could make a go or no-go decision whether they were still useable or not.

    As Ash pointed out, shaving changes (retards) the valve timing, and since adjustable timing gears for these engines aren't widely available, you need to know whether the heads & block have been shaved before you buy an engine. Metal that has been shaved off "can" be replaced by thicker head gaskets, but that's sort of a kluge, and they can't really be depended on for higher boost.
     
  6. ngdave11

    ngdave11 White Lightening Project

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    WoW... no postings?
    This come from 94 SC400
    Just got this back from the machine shop, Valve job & decked
    *Disclaimer* I just got my measuring tool, but I did several measurements.
    RHFront.jpg
    RH Front
    RHBack.jpg
    RH Back
    LH.jpg
    LH Still on block unmolested as far as I know.
     
    Last edited: Mar 9, 2018
  7. cribbj

    cribbj "Supra" Moderator Staff Member

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    ngdave, thanks for your additional data. It'll be interesting to see how well your timing belt fits now, and what you come up with for valve timing.

    Did your machinist give you any numbers on how much metal he took off on the deck & head surfaces?
     
  8. ngdave11

    ngdave11 White Lightening Project

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    no they didn't.
    I'm kinda new to all this, and with me asking a bunch of questions when picking it up, he kinda was ready for me to pay the bill and go! lol
    It kinda sounded like it would be a very little amount, but i wish i had asked that now.
    If or when I take the other one in, I'll make sure to ask!
     
  9. ngdave11

    ngdave11 White Lightening Project

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    Another Head I was able to document. 91 LS400
    64.11.jpg
     

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