How to tell the difference between a tall deck and a short deck 454?
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How to tell the difference between a tall deck and a short deck 454?

  1. #1
    1976 Sanger Flattie Running_on_Empty's Avatar
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    Default How to tell the difference between a tall deck and a short deck 454?

    How to tell the difference between a tall deck and a short deck 454?

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  3. #2
    92 KURTIS RUNNER BOTTOM
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    Its an 1/2 inch, you will need spacers if you use your manifold off a short deck and try to install it on a tall deck. spacers from the heads to the manifold and from the manifold to the block, usually a 427 truck block is a tall deck and the after market blocks can be ordered that way or you can measure it, and i"m sure some one here knows where to measure from
    Last edited by BAD REACTION; 03-27-2008 at 05:59 PM.
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    Some guy obnoxious001's Avatar
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    Quote Originally Posted by Running_on_Empty View Post
    How to tell the difference between a tall deck and a short deck 454?
    Use the casting number and look on Mortec, that's the easy way.

    Otherwise measure from the top water pump hole to the deck surface. A standard deck block will be roughly .200", and the tall deck roughly .600". The actual difference in the blocks is .400", not 1/2". Tall deck is 10.2" deck, standard is 9.8". Note that now days you can buy several different manifolds that fit tall deck engines with no spacers.

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    Senior Member ColeTR2's Avatar
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    Quote Originally Posted by Running_on_Empty View Post
    How to tell the difference between a tall deck and a short deck 454?
    I have never heard of a tall deck 454 only a 427 If you want to build a big cubic inch BBC I'd just go get a new after market block. Once you do all the machine work on a old tail deck block you will find out it's only a few hundred more for a new block that's way better. And you can make it even bigger.

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    Riser oil passage front of block.

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    gn7
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    well...not exactly, if it has a riser in the front it is a truck block, but I have two tall decks that DO NOT have the riser and the interesting thing about those two blocks is they have WAY WAY more room in the crank area, cleared 4.25 with tons of room, no where on them do they say TRUCK or MARINE which the other one does, and they are very very late castings.

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    Interesting. I never saw one that did not have the riser. Even the thin wall casting late model replacement I saw.
    Ok. Scratch that. LOL

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    Senior Member rocket98's Avatar
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    Back in the day.......I ran a tall deck high nickel simease block......can you tell me what this was .......I was only the driver and they won't tell me anything...........no bs

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    Part # 14044808 "Green Marine" If I remember right.

    http://gilbertautoparts.com/ChevyBar...tie4250td.html

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    gn7
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    Quote Originally Posted by Fiat48 View Post
    Interesting. I never saw one that did not have the riser. Even the thin wall casting late model replacement I saw.
    Ok. Scratch that. LOL
    NO! not at all, as far as I know, if it has the riser then it is a truck, But two others I have where from what I understand, a short run the GM did before they shut the tooling and line down on the 2pc rear seal tall deck mark IV blocks, some one in Las Vegas grap them ALL (More than likely connected) and then sold all off. I got one from Chet Herbert and the other from a guy at the Long Beach swap meet, and both had the worst machining tolerance wise I have ever seen from GM

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    Default Little story

    I used to pick them up at swap meets all the time. Tall decks were all I ran. Once I was at Long Beach and picked up one that was a very clean casting. Much cleaner than any of the others I had seen. Naturally I grabbed that one next time I needed a block. I ran most of them .100 over...just part of the combo I did.
    I bored this one .100 over..thought nothing of it. It split 2 cylinders while the car was just idling...warming up...at the first race.
    That block had a 7.4L (I think?) cast into the side of it. I asked the local dealer about it and he said GM had run short of 427 tall deck cores and had done this late casting which was pretty thin. Never came across another one.
    That's what I was told anyway.

  13. #12
    gn7
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    neither of mine sonic well enuff for a .100 bet you had one of the same deals.

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    How much material is between the water pump boss and the deck? Pretty much a huge visual difference in this area. Between std deck and tall deck.

    And core shift is visual where the water pump cooling holes, cam bearing bosses and oil galley holes are machined relative to the casting bosses.
    Last edited by Infomaniac; 03-27-2008 at 08:54 PM.

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    Some guy obnoxious001's Avatar
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    Quote Originally Posted by Infomaniac View Post
    How much material is between the water pump boss and the deck? Pretty much a huge visual difference in this area. Between std deck and tall deck.

    I posted measurements back in post #3. If he doesn't have more than one block to compare, or much experience handling them,and didn't want to check Mortec, it should be a quick and dirty way to tell the difference.

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