NOS 340 EXHAUST manifold

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Treblig

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I'm puzzled?? I have this NOS, never been used, covered with cosmoline, dealer tagged 340 manifold. Normally I would just sell it like all the other manifolds I sell but it seems to have a casting date of 1978 WHICH IS IMPOSSIBLE!!! From my research I know that these manifolds were made up to 1973 for the Dart, Challenger and Barracuda. It has the signature 1 7/8" exhaust hole like all the other (small hole) 340 manifolds I have so that part makes it a correct 340 manifold even though the year/date makes no sense. The part casting/number is also correct and very crisp just like the clock time. Can anyone make sense of this anomaly??? This would make a great addition to somebody's restoration.

PS - The cosmoline makes some of the casting numbers/letters a little unclear, they are actually very crisp (in person) but I don't want to rub the cosmoline off because it's probably been in this state for 40 years. I did remove a little cosmoline from the year date because I was looking for a "73" but found an "78" and couldn't believe it so I removed some of the cosmoline to make sure.

thanks,
treblig
 

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Cast later for replacements? Maybe they didn't cast enough shelf stock during the first year runs.
 
My guess at best is that they still would have been manufacturing service parts into 78. The cars were only 5 or 6 years old at that point. But as I stated that's just a guess.
 
Yeah, I don't see why it couldn't be a service part. In fact, it must have been, as it was obviously not installed on a car from the factory. Probably was the last batch of that part, though.
 
That would be interesting because all the Mopar exhaust manifold casting number charts don't show any after '73. I thought maybe the last number was just cast wrong?? I've never seen one with a casting date later than '73 (maybe '74), I wonder if anybody else has??

treblig
 
Armbruster motors is still in business. Selling Buicks.

Fratzog...that's amazing!! I didn't think anyone would bother to read the tag. The tag also has lots of info on it, maybe I need to look at it a little closer??

treblig
 
I have a later dated manifold exactly like that but dated 1977. I know where mine came from. A motor home with and original 360. I assumed they continued casting that pattern for RV and other odd applications. Dan
 
78 was a good year for cast iron or metallurgy. LOL
The fact that the heat riser is new draws my interest.
 
78 was a good year for cast iron or metallurgy. LOL
The fact that the heat riser is new draws my interest.

Yes, the heat riser has a thick coat of cosmoline smathered on it. You can see the shiny surface of the metal under the coating.

treblig
 
I have a later dated manifold exactly like that but dated 1977. I know where mine came from. A motor home with and original 360. I assumed they continued casting that pattern for RV and other odd applications. Dan

Thanks for that 75Sport. It makes a little more sense now!! It's funny that the Mopar exhaust manifold casting number chart doesn't show these used on motor homes. So I guess Mopar used them where ever they needed a little more power (like a motor home).

treblig
 
Whats 340 about it, the 1 7/8? I had a service manager work with me and he told me they stocked/produced stock for 7 years after production.. some sort of regulation...could have been blowing smoke.
 
Whats 340 about it, the 1 7/8? I had a service manager work with me and he told me they stocked/produced stock for 7 years after production.. some sort of regulation...could have been blowing smoke.

The casting number (3418623) and the size of the exhaust hole is the only way you can tell a 340 (like this one) from the regular non-hipo manifold. A regular non-hipo 318 manifold has a 1 5/8" as opposed to 1 7/8".
Unless someone else has more/better information....
Treblig
 
That's the best before date , you have to throw it out , it has gone bad .
 
That's the best before date , you have to throw it out , it has gone bad .

Your right!! I have to "throw it out" in the "Mechanical Parts" for sale Section...LOL!! I have no use for it but I know someone else probably does??
 
...........I have had a 340 with a casting date of 7/11/77..............kim..........


Oldkimmer, I think that kinda explains it. If you had one with a '77 casting date then Mopar must of kept casting them well past 73/74. Now it makes a little more sense. I thought since the "3" could have been mis-cast as a "8" it would have made sense but with your post I realize that they must have kept casting them longer.
"75Sport" has a similar story and "Pishta" says that he was told that they kept producing them long after '73. I think the mystery is solved, now I can put it up for sale knowing that it's legit!!

thanks,
Gil
 
check the tag on it for a date.

I checked the tag for a date and wouldn't you know it.... I can read 197XXXX, where the last number would be on the paper it's stained and torn. Even with a magnifying glass I can't make it out!!

treblig
 
Awesome exhaust manifold for that 78 motorhome resto!

Not much value to a numbers freak because of the cast date.
 
Awesome exhaust manifold for that 78 motorhome resto!

Not much value to a numbers freak because of the cast date.


Yes, wouldn't work for an all original resto but it's brand new and many members use them on the early A bodies because they fit and flow better than the stock 273/318 manifolds. The 340 manifolds like this one have a 1 7/8" exhaust hole while the stock 273-318 has a 1 5/8" exhaust hole. Why would someone buy a used one when they can get a brand new one??

treblig
 
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