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