Things To Consider Regarding Date Coded Parts
I had a guy ask me about a part he was looking at for a restoration of a Max Wedge car. What he was trying to do is figure out whether the casting date on a particular crossram intake manifold would work for the scheduled build date for his car. This prompted a rather long letter back to him as to my thought's on the subject. Now let me say right here and now I AM NOT THE LAST WORD ON THIS, but I do think I have a fairly accurate understanding of how it works. For the sake of this subject and since after all this is a Max Wedge / Race Hemi web site lets use the Max Wedge crossram intake as the example part.
Max Wedge crossram intakes were cast on several different casting dates so the important thing is to get a casting date earlier than the build of your car. I have seen Stage-I intakes with later casting dates than Stage-II intakes and Stage-III intakes earlier than Stage-II intakes. Unfortunately I do not have a factual list of casting dates to go off of so a person has to consider all kinds of possibility's when trying to figure out what casting date is appropriate for the specific part they are looking for. There is no set time frame a part should precede the build date of the car but there are a few things to keep in mind when looking for date coded appropriate parts.
First we start with the intake manifold casting. A date is added to the mold on the day that particular casting is made so you can consider that date is Gospel. There is no variation, that's when it was cast. Then that casting goes to another department where it might sit and wait to have all of the machined surface work done. Then it goes to another department that sends the intake to the engine assembly plant or to a storage location until it is needed. As you can well imagine all of these steps take time and each time step can vary from one batch of castings to the next. Another thing to consider is the storage factor. Imagine a holding area in a room just for intake manifolds. Here they are waiting to go to machining. One stack goes up against the wall. Another stack goes in front of that stack and another in front of that second stack and so on and so on. As they keep casting intakes they keep stacking them one stack in front of the other. As time goes by the stack closest to the wall is the oldest by casting date and the stack at the front is probably a newer casting date. Which stack do you think will go to machining first? THE FRONT STACK. Then that front stack of intakes goes to machining and might possibly go through this storage process again. Meanwhile that first batch of castings sits against the wall in the fresh casting room. Eventually they will get to those castings but you can imagine just how out of sequence that casting is based upon a date code. What can happen, and often does is the first engines built might have later castings and later built engines have earlier castings, and even later built engines have castings close to the engine build date and so on and so on. There is not a guy in each department staging parts like dairy products, moving the oldest to the front to maintain freshness. This process can be repeated any number of times, both at Chrysler or their parts suppliers. This would include blocks, cranks, cylinder heads, intakes and other individual component parts depending on how they are staged at the manufacturers facilities. Now that I have thrown the most likely scenario out there it is also possible the batches are small and you get the freshest parts made on the closest to engine build dates. I'm just saying!
Bottom line is there are only three things that are gospel, casting dates, manufacturing dates and the fact that you will almost never see part date codes that are newer that the engine build or the car build. The reason I say almost never is there are times when cars would be side lined waiting for parts and the build date is already on the body. That happened more often than one might think (thanks to Walt Redmond for this information) but that would not be considered consistent with production standards. So the norm is individual date coded component parts should almost always precede the build date of the final product.
Let me say that I understand the importance of proper date coding of parts. In a hard core concourse restoration this stuff gets real critical and my hat is off to those with the constitution to follow through with that ideal without wavering. Concourse restorations are not for the weak pocket book at heart. That being said, unless you are doing a nut and bolt concourse level restoration don't let date coded parts ruin the experience of building or restoring a respectable car.
A good manufacture date code rule of thumb on standard production parts is about two months before the main assembly, so like on an engine the intake should precede the build of the engine itself by usually two months or more, sometimes but not always less than two months. Then you have to consider the time frame possibilities between the engine build date and the build of the car itself which can be as little as a week to as much as several months, depending on car orders and available engine assemblies plus the location of the engines. When you get to the engines question, how are they stored at the plant? Do the ones at the front get pulled first before the ones the furthest back in the storage area? Probably so, so you go back into that hole thing where the earliest engines are further back and the later engines get pulled first. See what I mean? In short, try to stage each part a month to two months before its next destination in the chain of assembly of a car and you won't be wrong.
June 20, 2010
(but this was written long before that; see how difficult date coding can be?)