What is the vacuum hose going to the air cleaner 68 LaSabre?

[Guest tony's68]

Thanks for all the help with my other questions. I am finishing up rebuilding the brake system and am just waiting for my brake drums to get finished at the machine shop. As I was cleaning up the engine, I found my power steering pump leaking very badly so am getting a rebuilt unit and replacing the lines.

I am wondering what the vacuum hose going into the bottom of the air cleaner is for. It comes from a tee in another vacuum hose and hisses when I disconnect it when the engine is running. It is connected to some type of valve in the inside of the air cleaner. There is also another hose that is connected and runs to the front of the air cleaner to another type of valve or something.

This is for a 68 LaSabre, Custom 400 with the 350, 4 door hardtop, AC, power steering, and power brakes.

Questions: what is the vacuum hose for? Is it necessary? I would like to dress up the engine compartment with new paint, new hoses, and chrome valve covers/air cleaner.

Any and all help will be truly appreciated.

Thanks!

[Larry Schramm]

The hose goes from a vacuum port probably at the base of the carb to a "thermac" thermal vacuum valve which should have two ports on it. My memory remembers a blue or green colored valve. The other side of the valve has a hose that goes to the vacuum actuator on the snorkel of the air cleaner. All of the vacuum ports are on the underside of the air cleaner.

I am fairly sure this is correct for this year... just from memory.

Look here. http://www.autozone.com/autozone/repairguides/GM-Camaro-1967-1981-Repair-Guide/Exhaust-Emission-Controls/Thermostatic-Air-Cleaner-THERMAC/_/P-0900c1528007db79