What's the deal with this offenhauser intake

[jerry6]

is it any good ? The port seems to be split upper and lower sections , just wondering if this would be a good replacement for a stock 340 cast iron intake

http://www.ebay.ca/itm/MoPar-Dart-3...r_Truck_Parts_Accessories&hash=item35b527bb5d

 

[1970Duster]

The stock 340 manifold flows quite well for a factory piece. You'll need the Performer RPM or Air-Gap to really beat that factory manifold.
That being said, the one you're looking at does appear to have the 340 port size on it.

 

[jerry6]

Just wondering if the split port design has any real advantage over stock 340 intake , for 128.00 might want to try it on my factory stock 340 , if it has better performance

 

[cudavert]

I seriously doubt it's got better flow than stock, since that divider takes up space. I think the selling point on that manifold is good low-speed torque, driveability and mileage. It's like having tiny ports when running on your carb primaries.

 

[Wheel Chock]

This design was introduced by Offenhauser to boost low end torque on low compression 70's engines, much like Edelbrock's SP2P. I've never seen any dyno or performance tests of it, but it seems that the only advantage over a factory 340 design would be weight, most likely at the expense of flow. Like the SP2P, this is an obsolete design.

 

[ocdart]

I think the selling point on that manifold is good low-speed torque, driveability and mileage. It's like having tiny ports when running on your carb primaries.

Exactly right on the good low-speed torque, driveability and mileage as 'cudavert' said. But there's more to that manifold.
Notice the smaller primary portions are on the bottom part of the runners and the larger secondary portions are on top. The bottom primary runners help keep the larger secondary runners cooler so you get a denser blend of fuel/air from the secondaries when they kick in. The smaller runners really give you lots of flow speed helping to keep the fuel atomized.
I ran one of these manifolds on my '69 340 Swinger back in late 1970/early 1971 and was very happy with it.
Depends on what you're looking for - street drivability or drag strip performance. This manifold will work good on the street but won't give you the high-PM, top-end flow of current manifold designs.
BTW, I sold my old Offy Dual-Port manifold about 1981 when I stupidly took my Dart off the road to build it to race full time. Sold it at an OCIR swap meet for $50.