A 482 Building Block

Discussion in 'Street/strip 400/430/455' started by 6455spd, Feb 23, 2021.

  1. 6455spd

    6455spd Silver Level contributor

    Starting to build a stage 2 482 with a 288-94 type cam, maybe around 500hp?
    I got my block sonic checked and at first i thought the numbers looked good.
    Now I'm having second thoughts about the passenger outer thrust side being way too thin.
    #8 is the worst at .157, and all of them are well under .200.
    It is at its stock standard bore.
    Any thoughts? Should i use a different block?

    buic sonic numbers.jpg

    Attached Files:

  2. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    So you are going to bore this block .038?

    That motor with 10:1 SCR, Stage2 heads, and that cam will make at least 550 HP
  3. 6455spd

    6455spd Silver Level contributor

    I have collected parts over the years and I realize 482 is over kill. It will be a .038 overbore.
  4. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    So you have to subtract .019" from all those numbers?
  5. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

  6. 6455spd

    6455spd Silver Level contributor

    yes - but the machinist can move the bore center slightly .010 off center
  7. 6455spd

    6455spd Silver Level contributor

  8. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    For comparison, here is a side by side comparison of your block, and the block that JW used for my current 470. Notice that some cylinders were moved to maximize cylinder wall thickness.

    Kind of hard to read my numbers, here's a better pic of my block numbers,
  9. 6455spd

    6455spd Silver Level contributor

    I see, so your thinnest point at #2 thrust wall = .174 - (.038/2 over bore) +.010 moved center = .165 at the thinnest point.
    What cam your you using and how much hp?
    To make matters worse, i have some pitting on this block so ill have to look at the scars to see if the bores can be moved as well.
  10. standup 69

    standup 69 standup69

    Like what you posted earlier a good machinist can move the bores slightly ..still a bit thin tho
  11. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    I am using a custom hydraulic roller cam, 230*/238*, 112* LSA, .544/.577" lifts, 602 HP @ 5900, 589 TQ @ 4900 RPM.
  12. 6455spd

    6455spd Silver Level contributor

    I doubt it will ever see 5500 rpm but I think I'll try another block...:( - just in case i ever want to switch to a more aggressive cam at a later date. Thanks everyone for all the input.
  13. Jim Weise

    Jim Weise 1000+HP

    I would ask Kenny if he moved the probe to a couple spots, or just tested the one area.

    While 3 times more labor intensive, that is whey we use a 3 place measurement in 4 spots around the perimeter of the cylinder. We are looking to get an idea of what the wall looks like.. is it all .160 thick, or just in one spot. I would imagine he moved it around a little, with that reading staring him in the face.

    Here is one that I recently built to just shy of 600 HP if I recall correctly..

    mb482 jpg.JPG

    Now, the thickness we want on the passenger side, in relation to major/minor thrust, is exactly backwards in Buick 455 blocks. Every one that I can recall is like this. Outside of passenger side thinner than the valley side... just the way it is.

    I did not bat an eye at this one, even with number 6 wall going toward .160 on the passenger side major thrust. And all the holes on that side below .0200 at some point.. The 3 measurements told me that the wall thickness is tapering.. and thicker up at the top, where the heat is much greater. In sonic testing, we are searching for thin cylinder walls, but not only to be weary of it breaking, also to realize that the thinner the wall, the more likely it is to distort, especially in the upper part of the cylinder, where we see the heat of combustion. This block is at or over my personal .200 major thrust side limit, at the top of the cylinders, where all the action is happening.

    Same goes for the sonic check on Larry's.. that pesky pass side minor thrust hanging right around .200.. but having the three dimensions gives me more confidence to use it.

    Usage of the engine is also a consideration here.. I would not use any of the blocks shown in any test on this page, (except for the one below) to build a serious race motor.. something that is highly loaded nearly the entire time it is running.. But for a street motor, where it is loafing along most the time, the concern is lessened.

    And we move the cylinders slightly to leave as much material as possible.

    The OP's block is a good example of one that would be best to go 4.320/4.325 with, if the walls were really nice.

    Now, if you have a another block, have it checked, there certainly is nothing wrong with using the best candidate you have available. I would want more information on that block to condemn it, what the lifter valley looks like, thickness of the decks ect.

    I have always wondered if Buick did not screw up when they overbored the 400/430 casting to make the 455. It appears that the overbore was shifted to the outside of the block. There might be a reason for this that is above my pay grade, don't know, but centerline is centerline, so it would have to be some math voodoo.. I have not tested enough 400/430 blocks to make a conclusion, but the ones I have done, do not have the thinner major thrust on the passenger side. In fact, they are the opposite of the 455.

    This is a 400.. I have a couple 430 sheets that are similar in layout, but thinner overall.. We only wish the 455 was like this... sonic checking would not be the "thing" it is now.

    TB 400.JPG

    Last edited: Feb 23, 2021
  14. BrianTrick

    BrianTrick Brian Trick

    Any time you alter the original rod/stroke ratio,rod length,comp height,etc.,you don’t want to use a traditional 455 cam. You’d be further ahead to have one ground for your engine.
  15. Bens99gtp

    Bens99gtp Well-Known Member

    Yes the walls are slightly thinner, but with the shifter adjust i would thinknit would live......its not a all out race motor here. Is it optimal not, will it totally live, more than likely
  16. 6455spd

    6455spd Silver Level contributor

    I can see the probe grease witness marks on the cylinders. Kenny only measured at the center of each bore.
    I do have access to another block but the lifter bores were not as centered as the one I had measured. Hopefully that doesn't mean anything.
    I will bring in both blocks to measure at the three heights per cylinder and go from there.
    In hindsight, I should have looked at the numbers before paying to have the block cleaned.
    Question - How long does it take to get each measurement? Once the equipment is out I imagine each measurement is only takes a few seconds.
  17. Jim Weise

    Jim Weise 1000+HP

    I will spend a good hour sonic checking a block... in 3 spots, 4 places around the cylinder.

    you have to measure, record, measure, record..

    How he does it is fine, as long as the center number is what we are looking for, the other two numbers are really only needed if the center number is questionable.

    I called and talked to Bruce for you, just to remind them that the higher density iron Buick used requires a different sound velocity setting on the tester.. at least it does on mine, and a couple I have seen. Kenny and Bruce are top notch engine builders, but this is one of those goofy Buick things that is easy to overlook.

  18. 6455spd

    6455spd Silver Level contributor

    Thanks Jim for everything you do.
  19. 6455spd

    6455spd Silver Level contributor

    I brought the block back to Kenny at the machine shop to recalibrate the density and measure the top and bottom of the cylinders in question.. Hoping for the best.
  20. 6455spd

    6455spd Silver Level contributor

    I probaby should have looked more into a custom cam but I'm into a 288-94 for now.

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