core 'revision' number...BS? BUSTED!!

Small Block Mopar Engine

  1. pishta

    pishta I know I'm right....

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    Member is selling a very early 340 cast block, 6/22/67. This would make it a very early casting. It has been said the suffix after the casting number (-4) may be a 4th core 'revision' and everyone is hard up on the -1 blocks being the best or thickest or having the least core shift. I don't back that theory. I personally think the blocks were cast 8 at a time in 8 boxes and possibly with 8 cores. (EDIT---2 at a time) The -x is the core or the position and is used in QC to identify what core or position it was cast in to identify casting faults, not to rank the block. Any believers?

    Note the 4 in the casting number.on such an early date casting, that doesn't support the core revision number theory but does support the 8 cores cast at once and this one was just in cavity 4 (EDIT --2 cast at once)
     
    Last edited: Nov 25, 2021
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    • Ironracer

      Ironracer Gearhead

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      Very interesting...
       
    • pauly

      pauly MOPAR or no car! FABO Gold Member

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      I always figured it was a box or mold type number, similar to the cavity number commonly seen on molded plastic parts. But, I’m not real familiar with casting processes either, so I could be way off base!!
       
    • eekvonzipper

      eekvonzipper My Member is Legendary! FABO Gold Member

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      Wow! They could pour 8 at a time??? Krazzzyyyy!!
      What exactly is Core-Shift tho? and how would you know if you had a Shifted one?
       
    • toolmanmike

      toolmanmike Moderator Staff Member FABO Gold Member

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      Ya that could very well be. I have never seen it in print that the -X's were revisions and not cavity numbers but who's to say. Let's getting the bottom of it.
       
    • pishta

      pishta I know I'm right....

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      Core shift is when one bank of cylinders has a heavier wall on one side (example) as if the sand core was not centered in the drag (lower part of box) as they were cast upside down. It can be seen in the cam tunnel as a slight offset. I know they cast 4 in one pouring, but perhaps the foundry had 2 or more pour stations for up to 8 or more cavities. I've had a -6 and and a -8
       
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      • RustyRatRod

        RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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        That's all horse shit geared towards getting a higher price for something. It's been pretty much proven crap through research and some common sense. It's common sense you don't want the lowest or highest number, because toward the beginning they were still working everything out with the new mold and toward the end they were at the end of their life span. An engine in the middle was generally the best for lack of core shift. ......but it's all splittin hairs anyway, because if the block passed inspection, it's not much different than any of the rest. I'd tell um to stick their core reversion bullshit up their ass. Sideways. With no lube.
         
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        • Alaskan_TA

          Alaskan_TA Well-Known Member

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          A bock mold revision resets every specification to right where it should be.

          So a 1 being better than any higher number is the 'BS' part to use your term.

          I have an 11 and a 12 here, but I have seen higher.

          block revision number 11.JPG

          block revision number 12.JPG
           
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          • kursplat

            kursplat FABO Gold Member FABO Gold Member

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            rusty, you got to quit holding back with your true feelings. it's not good to bottle up all that opinion. we're all here for you and want you to learn to express yourself fully...












            :lol:
             
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            • RustyRatRod

              RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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              Yeah, I think it was @Oldmanmopar that said he'd seen a 15.
               
            • RustyRatRod

              RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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              Yeah, it's gonna kill me one day. lol
               
              Last edited: Nov 25, 2021
            • RustyRatRod

              RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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              What? So you mean I actually kinda got somethin right? lol
               
            • gdrill

              gdrill If you drink, think, before you type...... FABO Gold Member

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              Now if we could just figure out the dates that they started with the new cores......... :)
               
            • pishta

              pishta I know I'm right....

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              Trying to explain why a 6/22/67 340 already had a -4 revision (going by core revision theory) so they already were on the 4th core mod or change? That's got to be one of the first batches of 340's out of the plant. I don't buy it: -1, -8 all the same within casting margin of error. Thats my theory if someone wants to prove me wrong with first hand knowledge of Chrysler casting methods. I seem to remember seeing a foundry video of 4 inverted V8 blocks being poured simultaneously.
               
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              • pishta

                pishta I know I'm right....

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                I dont think it exists....... sand cores were constantly being produced by the master molds. If there was a revision (some 400 blocks thicker webbing) it would be a different casting number altogether.
                 
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                • dadsbee

                  dadsbee FABO Gold Member FABO Gold Member

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                  My #'s 383 magnum in the Bee is a -12. Feb 1969 production..
                  beerestoration2015-2016 1056.JPG
                   
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                  • pishta

                    pishta I know I'm right....

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                    Last edited: Nov 25, 2021
                  • kursplat

                    kursplat FABO Gold Member FABO Gold Member

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                    could the revision # also be they just needed a new mold? one cracks or is dropped or whatever and it's a replacement #, not necessarily a change
                     
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                    • toolmanmike

                      toolmanmike Moderator Staff Member FABO Gold Member

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                      Sure could be. They probably started pouring at least a couple months before a new release. There is a lot of fine tuning to get things right for a production run on a new part like that. It's a pretty complicated process. 273's and 318's had been around for a few years and had been tweaked already.
                       
                      Last edited: Nov 25, 2021
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                      • RustyRatRod

                        RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                        Evidently, that puts to rest the "4" core theory, then, doesn't it?
                         
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                        • RustyRatRod

                          RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                          That could well be one explanation. And therein is the issue. Unless we can get hols of somebody that actually did that job, we'll probably never know.
                           
                        • toolmanmike

                          toolmanmike Moderator Staff Member FABO Gold Member

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                          @krazykuda might know. He was in Mopar production. I need to chat with my old neighbor. He had a pattern shop that did core boxes and revisions with Deere.
                           
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                          • krazykuda

                            krazykuda Well-Known Member FABO Gold Member How-To Section Editor

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                            I doubt they poured blocks 8 at a time...

                            The -8, -4 etc could be the mold CAVITY....


                            On the engine I worked on, they poured 1 or 2 at a time (can't remember for sure)....

                            They have many 'cores' that they put together in a 'core box' to assemble the mold for the blocks... One core box has about 6 or so cores in it to make the mold for a block... Each core is a negative of the metal... They have to identify each core so if there any problems they can trace it back to what cores are having the problems and correct them...
                             
                            Last edited: Nov 26, 2021
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                            • toolmanmike

                              toolmanmike Moderator Staff Member FABO Gold Member

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                              @pishta there weren't just one core box and core set for one block pour. May be they had 8 and the mold line got them ready to pour. The molds take a lot more time to construct that it takes to pour.
                               
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                              • krazykuda

                                krazykuda Well-Known Member FABO Gold Member How-To Section Editor

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                                They do 'pilot builds' at different stages of the design process before production...

                                There is usually one in Jan-Feb, and another build in April-May, just before launch to prove out the tooling is making good parts...

                                The Jan-Feb build is about a couple dozen and all of the vehicles go to the different design groups and vehicle development to test the cars to make sure that they meet the requirements... Including a few that go to the proving grounds to put miles on them to see how they hold up....

                                The same thing happens with the build in May... Those cars go to each of the different design groups and the proving grounds to put as many miles on them before launch to find any defects/problems... The pilot cars are usually driven 16 - 24 hours at the proving grounds to try to put 10,000 - 12,000 miles on them ASAP before the launch in June/July....

                                Any parts that are not off of production tooling in the May pilot must get a TSA (temporary substitution approval) to use a production quality prototype part and are placed on a tracking list... As soon as the production tooled part is available, they will then phase it into the build slowly at first until it is proven to be ready....

                                If they can't make the part properly and can't use a prototype tool, then that part/system is put on hold and not available in production until they get things in order... Like the shaker hoods for the 70 Challenger... They weren't ready for launch and they substituted the dual scoop R/T hood until the shaker hood tooling could be completed.... They don't want to stop building the car completely, but just restrict the components that are late... In extreme cases, they will push back the launch 3 -6 months if needed....

                                The Jan-Feb build has a few prototype parts and mostly production parts as they are available... The April-May build is supposed to be all off of production tooling...
                                 
                                Last edited: Nov 25, 2021
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