Where is the thermostat located on a 1986 Chevy Nova?

The thermostat on a 1986 Chevy Nova is located at the bottom of the engine, in the intake manifold. It's usually housed in a metal housing, which may be bolted directly to the intake manifold or have a gasket between it and the manifold. You'll need to look carefully beneath the engine, possibly with a flashlight, as it's not readily visible from above.