whats this part?, l-jet FI Options

[grasshopper]

this came off my 75 1.8 engine. What is it?

[lapuwali]

The hose barbs need to connect to hoses between the air cleaner and the plenum. This thing has a bimetal spring and a small heater in it, which is powered by that electrical plug on the end. The idea is that it opens when cold, allowing extra air past the throttle, so you have a fast idle when the engine is cold. The combo of the electric heater and engine heat warms up the bimetal strip inside and closes the air valve, reducing the idle back to normal as the engine warms up.

You can probably see daylight through the hole when it's open. You can test it by aiming a hair dryer or heat gun at it, and it should close up so you can't see light through it, or blowing through it becomes difficult. These things tend to fail once they're this old. They were used on lots and lots of L-Jet and K-Jet systems over the years, and I haven't seen too many that still work. They usually get clogged with goo and stick.

If yours is stuck, spray lots of carb cleaner into the holes and let it soak. Tap it (TAP!) against something hard. Put it in the freezer to see if it opens, then heat it up to see if it closes. Repeat all of that a few times, and it MAY unstick.