General Questions Place to post your questions that don't fit into one of the specific forums below.

Vacuum controller

Thread Tools
 
Search this Thread
 
Old November 5th, 2010 | 12:08 PM
  #1  
TRAIN RACING's Avatar
Thread Starter
Registered User
 
Joined: Oct 2010
Posts: 18
Vacuum controller

I have a quadrajet 4 b. On top a 455 1971 cutlass. How dow i hook up the vacuum controller that sits behind the oil filler tube. It has a port on top and three on the side. Im sure one goes the vacuum advance but after that..whew
Old November 5th, 2010 | 01:55 PM
  #2  
joe_padavano's Avatar
Old(s) Fart
 
Joined: Mar 2007
Posts: 48,406
From: Northern VA
Originally Posted by TRAIN RACING
I have a quadrajet 4 b. On top a 455 1971 cutlass. How dow i hook up the vacuum controller that sits behind the oil filler tube. It has a port on top and three on the side. Im sure one goes the vacuum advance but after that..whew
That "vacuum controller" is actually called a Thermal Vacuum Switch (TVS) and it's part of an early emissions control system called Transmission Controlled Spark (TCS). The purpose of TCS was to reduce NOx emissions by disabling vacuum advance in all gears except high (third on an AT, for example). The electrical terminals on the top of that TVS are contected to a pressure switch in the transmission that enables vacuum advance in high. At other times the line to the distributor is blocked and the hose is vented. The "thermal" part of the TVS comes from the fact that it is screwed into the coolant crossover on the front of the intake. Disabling the vacuum advance can cause the engine to overheat under prolonged idling or stop-and-go conditions. The TVS senses that and connects the vacuum advance directly to manifold vacuum if that happens. Normally the advance operates off ported vacuum.

The three ports on the side of the TVS are labled M, D, and C. The M port goes to direct manifold vacuum. The D port goes to the distributor, and the C port goes to the ported vacuum port on the carb. The top port goes to a vent port at the top rear of the carb.

Of course, unless you care about total correctness, most folks simply eliminate the TCS system (and the associated TVS) and connect the vacuum advance to manifold (or ported) vacuum. I don't want to start a manifold vs. ported vacuum flame war here, however.
Old November 5th, 2010 | 02:02 PM
  #3  
Danny Boy's Avatar
1972 98 & 1984 H/O
 
Joined: Jul 2007
Posts: 247
From: Hoffman Estates, IL
vacuum controller hoses

I hope this helps
Attached Files
File Type: pdf
vacuum controller.pdf (10.3 KB, 57 views)
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
oddball
Parts For Sale
2
December 9th, 2012 07:11 AM
beepac98
Ninety-Eight
0
May 15th, 2012 06:36 PM
Dan Wirth
Vintage Oldsmobiles
3
December 2nd, 2011 01:55 PM
69350rocket
Other
14
December 27th, 2010 03:15 PM
Jolly Green
Big Blocks
1
May 17th, 2008 06:04 PM




All times are GMT -7. The time now is 08:17 PM.