What cubic inch can you stroke a 350 to?

Discussion in 'Small Block Tech' started by C.Rob, Feb 12, 2018.

  1. Mart

    Mart Gold level member

    Everything custom is a tight squeeze. The frt crank throw needed stock removed to clear my stk stroke roller cam eng.

    Stroker builds will need close examination on assembly for fit & clearance also.
     
    300sbb_overkill and alec296 like this.
  2. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    Here is page 9 of his thread where the pics of the clearanced rods and off centered pistons are;

    http://www.v8buick.com/index.php?threads/350-rebuild-questions.303453/page-9

    juze cam cl.jpg

    off centered piston, juze.jpg

    He shows the weight of the Molnar rods as well, a hefty 628.9 grams! almost 100 grams more than a nascar take out rod. Makes sense though because they cost WAY more, you're getting more for your $$.:rolleyes:
     
    FJM568 likes this.
  3. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    To be fair though, those Molnar rods were one of the first sets they probably sold, hopefully they corrected them by now?
     
  4. Extended Power

    Extended Power Well-Known Member

    It's too bad photopail started extorting money for 3rd party hosting of pictures...I had some good pictures of the clearance issues we had with our stroker build.
    Issues were not limited to:
    -poor machine shop skill set on first crank= junked crank (meme of the little rascal throwing money out the window comes to mind.)
    -roller cam= rod clearance issue between lobes of cam and rods....EVERY rod.
    -roller rockers= clearance issues on rocker towers.
    -roller cam/roller lifters= custom length push rods.
    -stroker build= custom order pistons because of pin height, & deck height

    In the end though, my Son and I learned a lot together...and those will be cherished memories forever.
    ...and the engine runs awesome too!

    Stroker engine size: 373.5ci
     
    MrSony likes this.
  5. sean Buick 76

    sean Buick 76 Buick Nut

    No they have not made any changes. I showed the pics to Tom Molnar and he thinks it must be core shift causing the issue of the offset..
     
  6. 8ad-f85

    8ad-f85 Well-Known Member

    Core shift on a forging?
    Forgive me asking second hand info.
     
  7. sean Buick 76

    sean Buick 76 Buick Nut

    I’m not sure the reasoning, that’s just what he said.. he said when they tested the rods they were centred in the piston pin...
     
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  8. 8ad-f85

    8ad-f85 Well-Known Member

    I know there's some misunderstanding with jargon because of going through a couple of people, but core shift is a term more associated with a sand cast part.
    It's a forging die that can pound out many thousands of the same part to shape.
    Normally if a forged part doesn't have enough material on one side to allow finish machining after being 'inspected' for a prototype or production run in which it passes the first time...it would strongly be suspected that it isn't the same forging.
    If it happens after the first one or run was proven, then there was a problem or change with the machining or the process afterwards.
    I get that the dies might not be specific to this engine, and that most are made from an existing blank that can cover several part numbers with some deviation in dimension.
    Obviously it isn't likely that a Buick specific rod blank die has made a hundred thousand rods and that the basic raw part has "shifted".
    I'm guessing the offset rod beam was an oversight while adapting an sbc rod to work with Buick?
    If the part exists only because of the availability of some current forging, which has an insignificant change from the OEM's version, then that's perfectly fine.
    We are lucky to have parts available.
     
  9. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    He was referring to the block having core shift, NOT the forged rods.
     
  10. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    What did he say about the cam clearance issues with a standard stroke with those rods?
     
  11. 8ad-f85

    8ad-f85 Well-Known Member

    Thanks for restating my thoughts in a more clear manner.
    Are you suggesting that machined features shown on the block's print are subject to changes based on core shift, such as the location of the cylinder in reference to the rod throw as one example?
     
  12. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    This issue for the core shift;

    [​IMG]

    This has NOTHING to do with any type of core shift;

    [​IMG]

    That would be a machining issue because that kind of rod even though it went through a forging press, gets machined on ALL surfaces and then shot peened, then the bores get a final hone.
     
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  13. sean Buick 76

    sean Buick 76 Buick Nut

    Yes that is what Tom suggested... since it wasn’t my engine I simply made him aware of the issue and left it at that... He suggested block core shift as a possible cause for the issue. I also pointed out that there was interference with the cam. I’m sure Tom and TA will iron out the issues, not many sets in use yet. Mark Demko has a set, using them in his current build so maybe more of this will come to light during that build.
     
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  14. 8ad-f85

    8ad-f85 Well-Known Member

    Derek, we are in complete agreement. I'm not Farming you. (Just kidding Gary!)

    The block being core shifted should not have anything to do with a cylinder being mislocated.
    It would mean the cylinder walls or whatever would visually appear thicker on one side and thinner elsewhere due to the fact that boring machines do not locate each feature based on visual centering of a casting.
    I've never checked, so I'm asking if there are blocks with cylinders proven to be severely mislocated as a result of bad castings and the foundry's fix was to deviate the print with approval from Buick?
    We aren't talking about a normal variance of maybe .005" or even a larger one approaching total tolerance stack up or what might affect other major features and their own tolerance range requiring an approval from engineering...we are looking at a shift of about .100", so the statement of 'core shift' seems unlikely.
    I do know it's possible, having been involved in these types of blueprint changes.
    If that IS the case, are all of the Buick 350's deviant from print or is there a range of years/date codes?

    I'm sure anyone involved in making things can iron out 'basic' production issues.
    I'm questioning what's being referred to because it doesn't make sense as described from a manufacturing standpoint, and I can plainly see the pics. Maybe I'm missing something here?
     
  15. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    That's what I was thinking as well, machining is within spec to the rest of the machining and the core shift would be internal that couldn't be seen by the naked eye except for offset cast in bosses and such.

    I suppose that block could be an isolated incidence?
     
  16. 8ad-f85

    8ad-f85 Well-Known Member

    I'm guessing that's not what is being talked about.
    When you move something major by .050-.100" there's so much more to deal with. (if that's what I'm seeing)
    Bolt patterns and everything else with it or is the entire bank shifted? Brackets and bosses?
    Is it a shifted piston casting?
    The water jacket location would be irrelevant.
    That cylinder looks well centered.
     
  17. sean Buick 76

    sean Buick 76 Buick Nut

    I think we need to see a few more engines go together with these rods to give us a better picture of the situation... if I had purchased these rods I would have pushed the issue but being that I have no cart in this race I just made Tom Molnar aware of the issue...
     
  18. 8ad-f85

    8ad-f85 Well-Known Member

    I think some simple measurements would clear anything up before experimenting with a few more engines and the purchase of rods.
    Rods being offset isn't any big deal at most of the power levels being contemplated anyways.
     
  19. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    Went back and read the thread, I think it is a block issue, possibly bad machining, here is what Juze wrote;

    "noticed passenger side rods are not center in piston, could this be problem? Unless they don't hit to pistons it's ok? Driver side is much closer to center."
     
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  20. 8ad-f85

    8ad-f85 Well-Known Member

    Is it possible that he installed the rods with the chamfer the wrong way on the one bank?
    (I suppose it's already been asked in the old thread)
     

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