I have a 71 Cutlass. Wondering if manifold exhaust from a Olds 307 engine would fit my 350.

 

The bolt pattern is the same however the actual volume of the exhaust ports in the manifold may be smaller than that of your 350, either in actual dimensional size (width x height) or (width x height x depth). I have a 307 manifold and when compared beside a 455 manifold there is an obvious difference, the 307 is much smaller. As I mentioned, don't know if it will be that evident between 307 and 350 or not. In a pinch, you could use it. Note that your down tube may not mate up to the manifold and may require some modifications.

 

Actually, it depends. The cast iron 307 manifolds should fit fine. The stainless tubular manifolds have smaller ports and may or may not seal properly to earlier heads.

 

I have exhaust manis on my 350 right now.

The 350 manifold didn't fit the body since the exit was right on top of the motor mount, the 307 manifolds exited behind the engine cross member.

A "14" and a "17" will work, these were made from 81 to mid way thru 85. As long as they are completely open in the middle port, they will work.

14 is the left side and the casting number is 22503678

17 is the right side and the casting number is 2506300

This is what I have, until I get my headers