On a Chevy 409 which valves are exhaust and intake?

On a Chevy 409, like most V8 engines, the valves are arranged in a specific order within the cylinder head. There's no single "intake" or "exhaust" valve; each cylinder has two valves, one intake and one exhaust.

To determine which is which, you'd need to:

* Consult a service manual: A factory service manual for a Chevy 409 will have diagrams clearly showing the intake and exhaust valve locations for each cylinder.

* Look at the cylinder head: The intake valves are generally larger than the exhaust valves. Also, the intake runners leading to the intake valves are usually larger than the exhaust ports. However, this is not always a guaranteed method for identification.

* Use a valve spring compressor: When you remove the valve cover and use a valve spring compressor to compress the springs, you'll be able to see the valve stems. The intake valve will usually have a larger diameter stem.

Without visual inspection or a diagram, there's no way to definitively say which valve is which.