Hello,

I was wondering if the big block exhaust manifolds would bolt up to the small block 350 and what would be the benefit of doing so would it breath better as I'm thinking the big block has larger ports on the inside also they're setup for dual exhaust without having to bolt a plate on.

 

All Olds heads have the same exhaust flange shape and bolt spacing, so yes, the BBO manifolds will bolt to the heads. Unfortunately, if you are trying to use the individual runner W/Z manifolds from the 69-72 A-body cars, these will NOT clear the rest of the motor, the motor mounts, or the oil filter adapter. Many have tried, none have succeeded. Not even Olds was able to do it, which is why even W-31 motors came from the factory with the same SBO manifolds as every other Cutlass. Other BBO manifolds besides the W/Z are smaller and may clear, but there is little value in that swap since they don't really flow any better.

And now someone will bring up the Thornton manifolds...

 

Why? It's been beat to death more than a few times. No need to rehash. Anyone who wants info on the Thorntons manifolds can use the 'Search' tool on the site. Saves time and avoids having to repost the same old same old....

Great info on the WZ manifolds though. Thx!

 

Yeah, just like the motor mount question...