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427, tall deck for a builder?

Discussion in 'The Garage' started by jk3078, Feb 4, 2006.

  1. jk3078

    jk3078 1/2 ton status

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    So I finally ran the numbers off my 427's, both are tall decks. www.MorTec.com lists a tall deck and a short deck 427. Is the tall deck as good a builder as a short and what is the difference exactly? Also the head numbers came back as oval port with open chambers, are these alright or should I be on the lookout for some other heads. I'm not looking to build a crazy race motor out of this (yet!) just something to make good power and rev. a little. I'm just trying to get my ducks in a row so buy this time next year I can drop one in my K5. Thanks for any help to a motor building newby.
     
  2. mountainexplorer

    mountainexplorer 1/2 ton status

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    What are the last 3 numbers on the head casting numbers?

    I've heard stories of some people using the tall deck blocks to build stroker big blocks out of (more room for a longer stroke), but I don't have all the info memorized on how to go about that.
     
  3. jk3078

    jk3078 1/2 ton status

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    "772" on one I didnt pull the valve cover on the other one, in a bit of a rush today.
     
  4. mountainexplorer

    mountainexplorer 1/2 ton status

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    772's I think are the same casting heads I have on the 454 in my Crew Cab right now. Can't say I know many specifics on them or how they compare to other open chamber oval port heads. They appear to be a truck application only. I'd "guess" to say they don't quite flow as well as some of the pass car heads like 781s.
     
  5. jk3078

    jk3078 1/2 ton status

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    So 454, 427 use the same heads? If so what other motors might I look at for donor heads?
     
  6. mountainexplorer

    mountainexplorer 1/2 ton status

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    If I remember correctly- and if my information source was accurate- someone told me before that the talldeck blocks and regular blocks used the same heads. Just the block and intake used was different. If what I was told is true, you should be able to use any BBC head including closed chamber 396 heads, 402 heads, and 454 heads.

    I'm not stating this as fact, but this is what I am under the impression of. (I had thought heads would be different as well until someone told me this)
     
  7. 3 on the tree

    3 on the tree 1/2 ton status

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    A bunch of Chevy "truck only" motors had smaller intake valves than the passenger car motors. I would bet that the tall deck 427 falls into this category. Find a set of heads off a 1 ton or smaller 454, to get bigger intake valves.
     
  8. tarussell

    tarussell 1/2 ton status

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    JK3078 - Production tall deck blocks are fine to use but might cause some minor problems if you are not informed when making part selections.
    Tall deck blocks are 10.2" at the deck ( measurement from crank center line to the deck of the block ) and regular blocks are 9.8" tall. The "V" only gets wider as the deck increases so that is the reason for the different intake on a T/D block. The aftermarket can offer intakes that will allow you to use a standard height dist. and you should not have much problems with exhaust manifolds and frame rail clearances or headers if chosen.
    If you are not going to increase the rod length, and use a 3.76" stroke, you will need to use a four ring piston or get a set of custom height pistons made. GM made the T/D block to have room for the extra piston ring in H.D. applications and the race world uses the taller deck block to allow room for longer rods - longer strokes and such.

    The cylinder heads will bolt up but be VERY careful in your choice of which head to use. There are several varients of the "oval port" head and not all are created equal. Most heads used on T/D motors were designed to have a power curve similar to a diesel engine - meaning that they pull like nobody's business at idle all the way to 3,800 RPM and than flatten out big time. The ports are made for velocity at the bery bottom end of the scale where a work truck engine spends all of it time.
    Try and stick with heads similar to the 781's / 049's - they make fantastic power all across the power band and are easy to find.
    I hope this helps shed a little light on you motor question . Good Luck ! Tom
     
  9. sweetk30

    sweetk30 professional hooker Premium Member

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    yep what he said is correct. and the distributer is taller also.
     
  10. bayou blazer

    bayou blazer 1/2 ton status

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    Summit sells intake manifold adapters to allow the use of any of the standard deck aftermarket manifolds out there. I think that Milodon makes them. Most of the dedicated tall deck manifolds out there are for the hard core racer that are using the block as a foundation for a big inch engines.
     
  11. nstarry

    nstarry 1/2 ton status

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    I heard you could run the 366 tall deck engine heads and bump the compression nicely and get a very stout motor !? just heard it have know idea if thats true
     
  12. jk3078

    jk3078 1/2 ton status

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    Good info guys, I'm starting to get an idea of what I want/need to do to get one of these in my truck. Someone I talked to today brought up the idea of shaving the deck down to make it a short deck, would this work or do the internals of the block not alow it? Great posts, keep 'em comin'.
     
  13. tarussell

    tarussell 1/2 ton status

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    Bad idea on the shaving down that much on a production type block - warpage and bad things will happen if you try that.

    Tom
     
  14. jk3078

    jk3078 1/2 ton status

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    Yea its a .4'' differance, thanks.
     
  15. sweetk30

    sweetk30 professional hooker Premium Member

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    if you want a short deck that bad sell the tall decks to the racers rather than trash them.
     
  16. jk3078

    jk3078 1/2 ton status

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    Hey, easy man, I'm not going to do it just getting info! I'm actually thinking maybe somekind of stroker kit might be neat....
     

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