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Thread: 4ag deck/piston hight

  1. #1
    anti blasphemy ! Carport Converter
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    Default 4ag deck/piston hight

    hey all,
    weres the measurement to measure deck height (e.g from top of coreplug to deck) ?
    because my pistons are slightly above my deck, the pistons are 8.9:1 ze pistons (with ae101 block) and im not shaw how much the block was faced before i had it but i was under the impression that the engine had never been apart. I could use a thicker headgasket but i dont wont too, i have my .8 mls.

    ive seen the answer somewhere on here but i tryed seaching but found nothing.
    Last edited by fixeruperer; 16-07-2008 at 03:53 PM.
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  2. #2
    Senior ****** Carport Converter Sam_Q's Avatar
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    Default Re: 4ag deck/piston hight

    I thought its normally checked by fitting a straight edge over the bore and then using a feeler gauge from that to the machined edge of a piston. Beats me how they do it when the piston is proud of the deck.

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    Default Re: 4ag deck/piston hight

    the same way, but using the feelers on the block.

    do the pistons sit flush with the deck originally ?
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  4. #4
    AVGAS DRINKING Carport Converter 30psi 4agte's Avatar
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    Default Re: 4ag deck/piston hight

    thats one way of doing it. You can actually buy a deck micrometer , which you put against the block / deck and wind down to touch the piston. You would then read the gauge just as you would a micrometer.

    As for the spec i dont know it off hand but can get it out of the bible tomorrow for you if nobody off of here knows it.

    FWIW my pistons were about .2mm under.

    Your rods mabe slightly (.1 - .3mm) longer than std causing the protruding deck height.

  5. #5
    AVGAS DRINKING Carport Converter 30psi 4agte's Avatar
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    Default Re: 4ag deck/piston hight

    Was the block line bored ? that could also cause a different deck height if not done right.

    How far does the piston stick out?

  6. #6
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    Default Re: 4ag deck/piston hight

    yeh that would be great if you can thanx man.

    well with the rods i wouldnt have thought so as i think more people would have said something ....... i hope

    yeh it was line bored in good hands so i wont worry about that just yet.
    i havent measured it yet but it looks about .013" - .015" ill check it tommo.
    Last edited by fixeruperer; 16-07-2008 at 10:03 PM.
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  7. #7
    Senior ****** Carport Converter Sam_Q's Avatar
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    Default Re: 4ag deck/piston hight

    Quote Originally Posted by fixeruperer
    the same way, but using the feelers on the block.

    do the pistons sit flush with the deck originally ?
    I feel kinda stupid now for not thinking of that!

    I have seen a 20v measured to be 0.03mm to the deck height, assumed to be stock but you never know for sure ever do you

  8. #8
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    Default Re: 4ag deck/piston hight


    ah ok yeh i thought they were a tad under, ill get the tolerance off 30psi so i know where im at.
    thanx.
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  9. #9
    AVGAS DRINKING Carport Converter 30psi 4agte's Avatar
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    Default Re: 4ag deck/piston hight

    To be honest i wouldnt really be very concerned about it!...... I will get the specs for ya but even if it isnt within spec i still wouldnt be worried.

    The only real difference i see it making is to your calculated comp ratio ......but even that would be marginal

  10. #10
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    Default Re: 4ag deck/piston hight

    Im concerned about everything , but yeh those specs would be great then i would know where my block and all the others are at thanx.

    Im slighty worried about the compression but i do have some overlap to play with so hopefull all is well, ill work out the c/r and see how bad ass its going to be.
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    AVGAS DRINKING Carport Converter 30psi 4agte's Avatar
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    Default Re: 4ag deck/piston hight

    Well that makes two of us concerned about everything nuts then...

    After searching the bible page by page i didnt find any spec for it. I couldnt even fid a spec for the overall rod length...... now i know i have seen them before but cant remember where.
    I thought it was the bible ( toyota 4a factory engine spec manual) but its obviously not!

    Have you tried bills site or the club 4ag tech reference ?

    P.S If you are so worried about the deck height and dont decide to use that block ..... Ill take it !

  12. #12
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    Default Re: 4ag deck/piston hight

    har har har i dont think so 30psi i want another 101gze engine aswell hehe just one more.

    yeh i went thru all the OG 4a websites i havnt been everywhere yet, havent had the time.

    Ive seen it before aswell but cant remember i think it might be on here somewhere.

    The stock 4A-G rod is 122mm nominal length (where its measured from i dont know, i would have thought from center to center) this is the page i got it from http://www.mr2supercharger.com/conrods.html.

    ill find the deck height measurement i have to, its like a game
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