273 with 340 exhaust manifolds

[Treblig]

I don't see any numbers, here are some pics, 65 Dart 360, manual steering,4 speed.
View attachment 1715418472
View attachment 1715418473
View attachment 1715418474
View attachment 1715418475
View attachment 1715418476

The passenger's side looks like the smaller hole 360 manifold or a standard 318 passenger's manifold, it's hard to tell without seeing how the down pipe hooks up?? You can tell because it's not flat across the outside surface. The large hole 360 manifold look like this:

The driver's ( from the looks of the down pipe flange) manifold looks like a standard 318 manifold. The 340 driver has a flat flange and mates dead up against the exhaust pipe flange. You can see on yours that the exhaust pipe flange "stands off", so it's not a 340 manifold. Here's a late 60s 340 driver and you can see the flat flange:

Treblig

 

[Avispa]

Appreciate the info, wonder why there aren't any numbers?

 

[Treblig]

Somebody may have ground the numbers off, on some factory manifolds the numbers are on the inside where you can't see. In the foreground you'll see a stock 318 driver's manifold with the bell flange like yours:

 

[Avispa]

Thanks again for the info.

 

[273]

This type of info is too limited to be of much use, IMHO. This is probably just a peak HP number; no info is given about the effects at lower/middle RPM's, and what the actual limiting factor was for peak HP.

I agree the hp curve matters more than peak, but highly doubt it’s making much more than 5 hp down low, especially when the restriction of the manifold gonna more at higher rpms. There’s little reason to put on expensive 340 manifolds when 360 or even magnum manifolds are gonna give you 95% of the power for lot less money.

 

[nm9stheham]

From the lack of info, you can't tell if the 340 manifold could make 10-20-30 HP more with other parts changed in the engine. In other words, the info is not about the manifolds by themselves, so seems to be meaningless as a fixed number. Isolated case info is not the same as generally applicable data. But hey, I just put headers on anyway! I 'butt-dyno' know how much my 351C lost when going from cheap headers back to stock manifolds....

 

[guido]

There have been a few early A owners who have installed a 60s 340 driver's manifold paired with a 360 magnum manifold on the passenger's side. I sell these manifold sets to FABO members, been doing it for years. I also sell the 70's 340 manifold paired with a 360 magnum passenger's manifold for use on 67 and up A bodies.

Treblig

 

[66jim]

IMO any gain using a 340 driver side manifold would be offset a lot because of the wicked bend connection needed on the outlet (narrow early A vs wider chassis late A) I don't think that manifold shootout test took that into account.