vacuum line question
Thread Starter
Drifting
Joined: Jan 2006
Posts: 1,554
Likes: 3
From: pasadena in the great state of TEXAS
St. Jude Donor '09-'10-'11-'12-'13-'14-'15-'16-'17
vacuum line question
i just had my quadrajet rebuilt and noticed a vac hose off of the air breather is not hooked up. the hose comes from the intake side of the air cleaner and i think is some kind of flapper that closes when the car is cold . where should these be hooked up. each intake has one and they attach to a piece on the bottom of the air cleaner and then go open ended. do they need to be hooked up and if so where do they go? i see no open vac lines or ports on the carb.
also the car idles fine but when i turn on the a/c the idle goes up to ~2000 rpms/ i know that there is an electric solenoid that pops out to increase the idle to account for the compressor running but is there a way to adjust the idle down when the a/c is on?
also the car idles fine but when i turn on the a/c the idle goes up to ~2000 rpms/ i know that there is an electric solenoid that pops out to increase the idle to account for the compressor running but is there a way to adjust the idle down when the a/c is on?
Le Mans Master
Joined: Sep 2002
Posts: 5,236
Likes: 898
From: Myrtle Beach SC
i just had my quadrajet rebuilt and noticed a vac hose off of the air breather is not hooked up. the hose comes from the intake side of the air cleaner and i think is some kind of flapper that closes when the car is cold . where should these be hooked up. each intake has one and they attach to a piece (port?) on the bottom of the air cleaner and then go open ended. do they need to be hooked up and if so where do they go? i see no open vac lines or ports on the carb.
also the car idles fine but when i turn on the a/c the idle goes up to ~2000 rpms/ i know that there is an electric solenoid that pops out to increase the idle to account for the compressor running but is there a way to adjust the idle down when the a/c is on?
Thread Starter
Drifting
Joined: Jan 2006
Posts: 1,554
Likes: 3
From: pasadena in the great state of TEXAS
St. Jude Donor '09-'10-'11-'12-'13-'14-'15-'16-'17
You don't state but I assume its the 78 L82 and if I understand your question and related description, sounds like that is the vacuum hose that comes out from two ports located under the air cleaner and routes to a port on the back side, bottom of the carb. There are color coded vacuum hose schematics that are great from reconnecting all those hoses. Seems like someone posted an electronic version some time ago here on the forum.
Both your shop manual and the emission sticker will list the specifications for adjusting the solenoid with A/C on. Your solenoid (M38) should have an adjusting nut but check the shop manual for proper adjustments.
Both your shop manual and the emission sticker will list the specifications for adjusting the solenoid with A/C on. Your solenoid (M38) should have an adjusting nut but check the shop manual for proper adjustments.
the solenoid looks like it can be adjustable i just wanted to ask here 1st , i don't have a shop manuel. thanks for your help...
Le Mans Master
Joined: Sep 2002
Posts: 5,236
Likes: 898
From: Myrtle Beach SC
I don't think technically it is an emission control hose but a "warm air" mechanism described as Thermostatic control. Thermac routes pre-heated air from the exhaust manifold into the air cleaner. The vacuum hose powers the flaps in the Thermac device and connects thru a temperature sensor, originally a green color that is located on the passenger side of the air cleaner base. On the L82, the driver's side connects to the probe underneath while the passenger side Thermac connects to a "T" which connects to both the other air cleaner port and the port on the base of the carb.
