Anyone use/adapt a 318 Exhaust Manifold to a 340?

[Dibbons]

I have two passenger side exhaust manifolds (casting #3418623s see photo) for the 340 I am putting together and I can't find a driver's side (casting 3418621). I have a pair of 318 exhaust manifolds on the '71 BBody I am working on. Will I be able to use the driver side 318 exhaust manifold on a 340 without major problems? It would only be temporary. Thank you.

 

[toolmanmike]

Will it work? Sure. Is it right? Nope. I would be more concerned about the exaust pipe you will have to make and re-make with the combination you are preposing.

 

[davek]

I would be concern of the engine not breathing right. 340 exhaust ports is bigger.

 

[Cranky]

I have two passenger side exhaust manifolds (casting #3418623s see photo) for the 340 I am putting together and I can't find a driver's side (casting 3418621). I have a pair of 318 exhaust manifolds on the '71 BBody I am working on. Will I be able to use the driver side 318 exhaust manifold on a 340 without major problems? It would only be temporary. Thank you.

View attachment 1726764

I would be concern of the engine not breathing right. 340 exhaust ports is bigger.

Could always port match the 318 manifold so there wouldn't be a step....

 

[oldkimmer]

Or let me see: u could possibly post a wanted ad. Kim

 

[kiwigtx]

Or let me see: (Insert sarcasm) u could possibly post a wanted ad. Kim

Fixed.

 

[DeltaV]

I was going to suggest checking with the FABO folks, but the OP already tried that route.

[WANTED] - Small Block Left Side (driver) Exhaust Manifold 3418621

 

[Nxcoupe]

Temporarily, yep, it'll work

 

[Bird 426]

Measure the vertical of the port, 340 is much taller. Check with a 340 exhaust gasket, check the head and then the manifold. I would say no, will not work.
Could not find a 318 heat shield/gasket when I rebuilt my 318 and tried a 340 exhaust gasket, stock cast iron manifold, no way.

 

[Bird 426]

So I guess we will never know, it's an old thread.

 

[Cranky]

So I guess we will never know, it's an old thread.

Well, it's not 'that old' yet lol

 

[Bird 426]

Op has only the opening comment, none after, that was September last year?

 

[Cranky]

@Dibbons Did ya get things fixed up??

 

[Dibbons]

Did ya get things fixed up??

Not yet. Still wording on the rebuild. Took forever to find a shop that refurbish connecting rods. Finally find a machine shop that specializes in diesel engines that can help me out with that @ $400 Mexican Pesos each (about $20 USD).