Thermostatic Air Cleaner Heat Valve ?

[54blackhornet]

Can any one please explain proper operation ? When cold, the valve is in the open position on my 71 350, you can easily look into the end of air horn and it's open , closing the path from the heat stove. I would assume it's supposed to be oriented to close off air from the air horn ? Correct ? Also any photo of carb vacuum source port on stock Qjet............Thanks Guys

[davepl]

The goal is to provide an airstream of about 110F (depends on the calibration of that vehicle and carb). So it mixes hot air from the air stove with "cool" outside air to achieve that balance. There's a thermostatic vacuum valve inside the air cleaner housing that regulates vacuum to the valve for this purpose.

When cold (perhaps with the engine just started and running so you have vacuum) shine a light into the snorkel, it should be closed, pulling all hot air from below. Once warmed up, it should be open, or at least quite a bit open, to get cooler air.

Manifold vacuum is what you want, so any manifold or carb port that is manifold works.

Common symptom is a tip-in bog on the throttle when cold or not fully warmed up. Sort of like a bad accelerator pump or secondary vacuum doors opening too quickly.

[54blackhornet]

Thanks for the information ! Mine is not working, it stays open all the time ? The vacuum lines running to air cleaner and charcoal canister where removed. Spent time setting choke properly, now on to the heat stove , determined to get "Olivia " running right in cold weather ! I read stories about how well they ran when new, but I have never seen it myself yet ? Thanks again......