Hello, I am going thru a 1971 Skylark and ran across this funny looking situation on the front of the 350 engine. I have never seen this before and wondered have any of you folks seen this or have done this? Thanks in advance for looking.
TCS = Transmission Controlled Spark. Keeps vacuum from advancing timing until transmission is in 3rd gear. Part of the Pollution control system. The blue/violet thingy is a resistor.
Thank you. Please, can you explain why the resistor was placed there? Resistors are to cut down current , but where is the current coming from? The transmission?
That would be my guess but I don't have a schematic at my fingertips. The current to the points is not 12v and must be stepped down to something like 8v (if I remember correctly). If you apply 12v to the distributor, the points will fry.
Brad, not to highjack this tread but do most members simply unplug the TCS or do they leave it connected and bypass the vacuum connection to improve performance?
I am guessing that the Canadian built or imported from U.S. into Canada did not have that TCS. My '72 GS 350 does not have it nor the Idle Stop Solenoid.
My guess is that most will disable it or completely remove anything to do with pollution control, this included.
My 71 had that it stopped the spark advance in 1st and 2nd gear This may have been an air conditioning part also since there was the extra power being taken from engine. The spark advance may have been on when the the air was on or it may have been off..not sure there. But I do know it was to stop the advance with the canister in 1st and 2nd gear. I eventually had to get rid of the spark advance preventer, could not see not having spark advance in 1st and 2nd gear. I also had a idle control that just had a spring on it and would slow down the carb from coming to completely closed for about 1 second then close to idle. This kept the engine from stalling with the air conditioner on. The idle sow down solenoid eventually quit working correctly, it would not go to idle. Had to get rid of that too.
I seem to remember a sticker that stated "For Export Only" on my car. The car would not meet California emissions & probably some states also. Where that sticker is now?? As u know, there is nor recirc pump on my car. Canadian emissions at that time did not reflect U.S. standards
The TCS was a pollution control device. It did not allow vacuum advance in 1st and 2nd gear, and then allowed it in 3rd gear. Buick engines using the TCS had relatively retarded timing at idle. This caused a tendency for the engine to run hotter. Part of the system included a thermo vacuum switch in the intake. If the engine reached 220*, the thermo vacuum switch would apply manifold vacuum to the vacuum advance, increasing timing at idle, and speeding up the idle speed, both of those intended to cool the engine down. Bottom line is the TCS is a performance and gas mileage killer that tends to make the engine run hotter than it should. I advise removing it completely, or if you are concourse restoration minded, disabling the system while leaving it stock appearing. The components of the system were different on different engines, but they functioned the same way. There was an oil pressure switch from the transmission that provided a ground in direct drive (3rd gear). Vacuum switches had an electrical connection, and there was a thermo vacuum switch as previously mentioned. I had the TCS system on my 72 Skylark 350-2bbl. Defeating the system was as easy as unplugging the electrical connection on the thermo vacuum switches. That allowed ported vacuum advance in all 3 gears. The engine had better throttle response and gas mileage. This is what the system looked like on my 350-2, This page from the 72 Chassis manual describes the system function.
LOL yeah I remamber reading that in my Chiltons book and pulled that off right now, mine was a 71. Had some friends impressed in how well it ran with 2bbl stock 350. I had just a straight Skylark non GS.
