Re: '64 PB Master Cylinder Date Coding
James-----
The VAST majority of Delco brake part castings that I've examined seem to have only the 3 digit "date" code that you're referring to, if they have anything, at all, that resembles a date code. I've never been able to determine if this series actually represents a date code (julian-style) or whether it refers to something else. In any event, assuming that it is a julian-style date code, I've observed MANY pieces that absolutely, positively didn't have anything that could be interpretted as a "year" coding. This includes 65-82 brake calipers (I've examined MANY hundreds) and 67-82 master cylinders (a hundred or more, too). So, it's apparent to me that if these 3 digit series are julian date coding, then, for whatever reason, there was no year coding included on the casting. That makes the 3 digit coding pretty much useless as far as determining "correctness" is concerned. Given, in combination, the "6 month rule" and the lack of a year coding that means that 50% of the castings out there would be "correct" for any car.
It's possible that the "2" or "3" seen below the 3 digit code is a reference to a year. However, it's also possible that it refers to something else. One possibility would be a mold number and there are many other possibilities, too. In any event and as I say, based upon my observations of other Delco brake part castings, there usually isn't anything that could be interpretted as a year coding. IF there is a STAMPED coding on a cast iron brake part, that coding usually does include a year. However, these stamped codings are the exception rather than the rule for Delco brake part castings.
The vast majority of these pre-1973 Delco cast iron brake part castings were produced at the old GM Central Foundry Danville, IL nodular cast iron foundry. Perhaps if we could find someone out there that worked there AND was familiar with their casting mark protocols we could help get to the bottom of all this.
James-----
The VAST majority of Delco brake part castings that I've examined seem to have only the 3 digit "date" code that you're referring to, if they have anything, at all, that resembles a date code. I've never been able to determine if this series actually represents a date code (julian-style) or whether it refers to something else. In any event, assuming that it is a julian-style date code, I've observed MANY pieces that absolutely, positively didn't have anything that could be interpretted as a "year" coding. This includes 65-82 brake calipers (I've examined MANY hundreds) and 67-82 master cylinders (a hundred or more, too). So, it's apparent to me that if these 3 digit series are julian date coding, then, for whatever reason, there was no year coding included on the casting. That makes the 3 digit coding pretty much useless as far as determining "correctness" is concerned. Given, in combination, the "6 month rule" and the lack of a year coding that means that 50% of the castings out there would be "correct" for any car.
It's possible that the "2" or "3" seen below the 3 digit code is a reference to a year. However, it's also possible that it refers to something else. One possibility would be a mold number and there are many other possibilities, too. In any event and as I say, based upon my observations of other Delco brake part castings, there usually isn't anything that could be interpretted as a year coding. IF there is a STAMPED coding on a cast iron brake part, that coding usually does include a year. However, these stamped codings are the exception rather than the rule for Delco brake part castings.
The vast majority of these pre-1973 Delco cast iron brake part castings were produced at the old GM Central Foundry Danville, IL nodular cast iron foundry. Perhaps if we could find someone out there that worked there AND was familiar with their casting mark protocols we could help get to the bottom of all this.
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