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Hemi Exhaust Manifold Casting Dates
#2830238
10/08/20 09:27 AM
10/08/20 09:27 AM
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North Dakota
6PakBee
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I finally found my pair of Hemi exhaust manifolds. They both have a date code that I can't decipher and haven't found any source to decipher them. The two date codes are 21MA and 13FB. Anyone have any insight into this? They look like this. I apologize for the poor quality of the 13FB but that is what it appears to be.
Last edited by 6PakBee; 10/08/20 09:27 AM.
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Re: Hemi Exhaust Manifold Casting Dates
[Re: 6PakBee]
#2830734
10/09/20 12:09 PM
10/09/20 12:09 PM
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Okay, let's go at this another way, does anyone know when Chrysler dropped the traditional date coding on the Hemi exhaust manifolds and went to the style shown above? By traditional date coding I mean this style.
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Re: Hemi Exhaust Manifold Casting Dates
[Re: dragon slayer]
#2831030
10/10/20 08:14 AM
10/10/20 08:14 AM
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Did direct connection make exh manifolds? Is that a World Block type casting symbol on the manifold? Maybe it is aftermarket???  No,they're not aftermarket or repop pieces. They came off a 1970 Hemi Roadrunner purchased new in late 1969 after about two weeks of use. I was there when the owner removed them and installed headers. I can't find any translation of the casting date format anywhere, that's why I'm hoping someone has manifolds with the previous date code format to at least try to identify when the switch was made. My guess, and it's only a guess, is that Mopar changed suppliers, hence the different date code format. But that is all speculation on my part.
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Re: Hemi Exhaust Manifold Casting Dates
[Re: 70HemiGTX]
#2831447
10/11/20 10:09 AM
10/11/20 10:09 AM
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Yes you did. Sorry about that. No need to apologize, that jogged the memory. Pasting the list that TWS posted and adding the second one of mine: 12JB = 12th day of September 1970 20JB = 20th day of September 1970 12JA = 12th day of September 1969 14LA = 14th day of November 1969 19FB = 19th day of June 1970 27MA = 27th day of December 1969 5MA = 5th day of December 1969 13FB = 13th day of June 1970 If this is indeed accurate that would put the car that my manifolds came from as a late 1970, not an early 1970 which doesn't make sense. Unless the 13FB is actually a 13FA (June 1969) which would make everything fit. And in answer to my thoughts about a changeover, this would indicate that 1969 is the first year for this goofy date coding. It would be interesting if someone had a Hemi manifold with a traditional 1969 date code on it.
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Re: Hemi Exhaust Manifold Casting Dates
[Re: dragon slayer]
#2831625
10/11/20 05:19 PM
10/11/20 05:19 PM
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Oh God, this all happened 50 years ago. But your point is well taken. I can see that I'm going to have to round up the owner of the car and see how good his memory is.
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Re: Hemi Exhaust Manifold Casting Dates
[Re: mccannix]
#2831810
10/12/20 09:02 AM
10/12/20 09:02 AM
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Like 6PakBee' manifolds that came off a 70 GTX, these came off a 70 Hemicuda that was driven home from the dealership, manifolds removed for headers for racing.....both numerically dated 11 21 9 Thanks so much for the post and the photos! This is another piece of the puzzle. With that late 1969 casting date in the 'traditional' format, could there have been two manifold suppliers with different formats in the '69/'70 time frame?
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Re: Hemi Exhaust Manifold Casting Dates
[Re: 6PakBee]
#2832012
10/12/20 05:23 PM
10/12/20 05:23 PM
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All original 1971 Hemi. Car built late 1971.
Sorry for upside down photos - iPad not cooperating.
Last edited by Transman; 10/12/20 05:25 PM.
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Re: Hemi Exhaust Manifold Casting Dates
[Re: A727Tflite]
#2832043
10/12/20 07:05 PM
10/12/20 07:05 PM
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All original 1971 Hemi. Car built late 1971.
Sorry for upside down photos - iPad not cooperating. Unreal. Your manifolds have the same exact casting date as mccannix's manifolds. For two cars a year apart. The farther we go down this rabbit hole the more interesting it becomes!
"We live in a time when intelligent people are being silenced so that stupid people won't be offended".
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Re: Hemi Exhaust Manifold Casting Dates
[Re: 6PakBee]
#2832051
10/12/20 07:19 PM
10/12/20 07:19 PM
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PA
70HemiGTX
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All original 1971 Hemi. Car built late 1971.
Sorry for upside down photos - iPad not cooperating. Unreal. Your manifolds have the same exact casting date as mccannix's manifolds. For two cars a year apart. The farther we go down this rabbit hole the more interesting it becomes! I didn't look at those date codes that close. Amazing.
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Re: Hemi Exhaust Manifold Casting Dates
[Re: 70HemiGTX]
#2832083
10/12/20 08:41 PM
10/12/20 08:41 PM
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Interesting. Hmmm. Well, are there any pictures of any "original older" manifolds that may be on their original cars? If someone could find a set that is known to be original to a car, and what date code style does it have? I'm wondering if they just used up what was in the bin at the engine assembly plant. Do you think the workers really cared about what manifolds they threw on the engines? As long as it fits..... Plus how far ahead were the engines built? What was the completed engine stockpile at assembly plants. Also what inventory control did they use? FIFO or LIFO? Did any engines that should have gone into earlier cars like 69 engines with solid lifters get into early 70 cars or vice a versa an engine built for with a hydraulic cam got put into a very late 69 car? To me these are all interesting questions. I agree. I have been told that an excellent example of LIFO were wheels. If demand was low, the inventory depleted slowly and the wheel date code and the car became farther apart. When demand was high and inventory was replenished frequently, then the difference decreased. And at the end of the year when the inventories were being exhausted, the date code could be months away from a car as the wheels first put into inventory were now being used. But this is what I was told once and you know the old saying about believing what you read and what you hear. 
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Re: Hemi Exhaust Manifold Casting Dates
[Re: 6PakBee]
#2832106
10/12/20 09:25 PM
10/12/20 09:25 PM
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Part number specific engines and transmissions generally should not be installed earlier or later than the model year they were released for.
Everything was tested and released by the BOM for a specific Model Year.
The engine and transmission plants shipped by part number only. Racks were shipped to the car plants, inventoried and were then released to the line.
As for assembly date codes within a part number, they could easily be out of order but usually if racks were moved incorrectly within the vehicle assembly plants.
That’s been my experience from 1986 - 2008. No reason to believe it was any different back in the day.
Last edited by Transman; 10/13/20 07:53 AM.
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Re: Hemi Exhaust Manifold Casting Dates
[Re: dragon slayer]
#2832160
10/12/20 11:34 PM
10/12/20 11:34 PM
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The exhaust manifold is not really a disposable part like a starter or water pump, or even a carburetor. So at some point MOPAR saw the writing on the wall for low production numbers for Hemi cars. No body is buying an over the counter exhaust manifold for a race motor. So I would think they had plenty of extra manifold to use up. 70 carbs wound up on 71 cars too. I imagine a lot of exhaust manifolds made it to the trash pile when headers were put on. Your point about stuff going to the trash - late 1969 a local Sunoco station had collected a pile of scrap behind the shop from doing race car and street racer work. It was time to clean up the pile. I remember seeing street Hemi intakes, exhaust manifolds and unknown oil pans, you name it. I sure wish I had taken that stuff.
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