Exhaust manifold id

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71RALLYEDART

71RALLYEDART

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Please help me identify this exhaust manifold. There is no casting number a 2 3\8 outlet and a flat outlet flange. Thanks also i beleive it is for a small block
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Thats a repop d/s 68-70 340 manifold. Thats why it has no casting numbers.
 
Hell no it doesn't make it worthless. What is the diameter / CC of the bolt holes of th outlet?
 
I've seen many of these where the casting number is very faint. They used to stamp them (imprint) the number and it wasn't a very deep stamping. For this reason the numbers would fade away to the point that you can barely see them or not see them at all. Without seeing it in person I can't tell if it's real or a repop. It looks real???

treblig
 
OK thanks guys. I have a passenger side 1 with a casting number that says it's a 70 and up 340, but the outlet diameter is different. I would guess that is part of a different set.
 
71RALLYEDART said:
The passenger casting number is 3418623. Is this one sought after at all?
Click to expand...


I believe the 623 is the 70s right side 340 manifold. It should have a 1 7/8" exit hole. The 623 was used opposite the larger 2 1/4" driver's side. I've never been able to figure out why Mopar would put one small and one large manifold on the same engine.
It has some value but not nearly as much as the 2 1/4", I sell the 623 for $90 -$120 depending on condition. Most people only want them if they're restoring a car and want it all original. Most everybody else would prefer a large 2 1/4" manifold on both sides of the engine.

treblig
 
They probably measured the backpressure in the system and determined the smaller hole was a better bet. I know the Magnum exhaust had a huge outlet one year then it went down for increased torque and the same HP. Worthless? Hardly!
 
In the 70s a matched set of factory 340 manifolds consisted of a large hole driver with a small hole (623) passenger. There are 2 1/4" passenger manifolds but I believe that majority of them are from the 60s and maybe very early 70s. I just sold these two 2 1/4" passenger manifolds last week.

treblig

DSC06269.JPG
 
the 623 is a 71-73 340 manifold.

The swept back 549 style ended with 1970 model year.

The driver side manifold may not have any markings in it and still be OEM.
 
I've had Mopar casting 623 manifolds dated as late as 76/77 so Mopar kept casting them, probably for replacements. All the post '73 623 manifolds I've had were original Mopar 623 castings.

treblig
 
They were also used on the A body 360 cars, probably 360 F body too. I quit with the list I updated at 73 because that was the last 340 production.
 
OK thanks for all the helpful info guys. I ! Not sure if I'm going to use them on my dart or get rid of them. I have to mull it over
 
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