1971 Cutlass 350. I've looked & can't see a valve on my car. Both sides go directly from manifold to exhaust pipe as far as I can see. Am I missing something? I wanted to be sure it wasn't stuck shut in the car I just bought. I though there was one in the right bank.

 

If the exhaust has been modified, it may have been removed.

 

Can't say that the 350 does not have a heat riser valve but I believe 1969 was the last year that one was used on 442 models.

 

'72 didn't have them, pretty sure '71 didn't either.
It's quite common for them to get thrown away at some point even if the car did come with it. They really weren't necessary unless maybe you live in an extremely cold climate and drive daily in that weather. Even then, there's plenty of heat under the hood without forcing a bunch of extra exhaust through the intake crossover.