Spark Control Solenoid - ?? thingy ??
Thread Starter
Instructor
Joined: Jan 2005
Posts: 101
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From: Ocean Gate, New Jersey
Spark Control Solenoid - ?? thingy ??
Can anyone tell me how this thing is supposed to work, and how to determine if it is working properly??? 
My car was running lousy under light acceleration until I bypassed this solenoid by connecting the vacuum advance line directly to the carburetor. This thing would click on and block any vacuum getting to the distributor so no vacuum timing advance was allowed - lousy.
My car was running lousy under light acceleration until I bypassed this solenoid by connecting the vacuum advance line directly to the carburetor. This thing would click on and block any vacuum getting to the distributor so no vacuum timing advance was allowed - lousy.
Melting Slicks
Joined: May 1999
Posts: 2,897
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From: Moon Township PA
There is a very good description in the GM Service Manual for the Transmission Controlled Spark. IIRC, the components of the TCS system are: the switch on the transmission that allows normal vacuum advance with the engine in fourth gear; the TCS timer on the firewall that allows the system to work after a period of time (30-45 seconds?) and in fourth gear; and the temperature sending unit in the right head (between the #6 and #8 spark plugs) that allows full vacuum when the other components are in - fourth gear and the time has been satisfied. When all of this is working, the solenoid opens (that is the "thingy" in the photo) allowing vacuum to the distributor. The GM Service Manual gives diagnostics and step by step procedures for the TCS system - at least it does in my 72. I would send them to you but I am not at home.
Many people disable the system by just running standard vacuum from your carb to the distributor. The timer is available used only but the temp sending unit is available from the catalog companies. The switch on the trans is also available but the solenoid is not. The good news is that the solenoid can be carefully taken apart, cleaned and reassembled. I have rebuilt three of these and they still work.
Gary
ps, as I mentioned, this is all from memory.
Many people disable the system by just running standard vacuum from your carb to the distributor. The timer is available used only but the temp sending unit is available from the catalog companies. The switch on the trans is also available but the solenoid is not. The good news is that the solenoid can be carefully taken apart, cleaned and reassembled. I have rebuilt three of these and they still work.
Gary
ps, as I mentioned, this is all from memory.
