cpmman Posted December 12, 2010 Share Posted December 12, 2010 Can anyone tell me how the vacuum lines run on top of the intake on the 1970 400BB? There is a solinoid then bolts on top of the manifold with one vacuum connection on one end and two vacuum connections on the other but not sure where the lines are supposed to come from and go? Possibly the air cleaner? It also has a electrical connector plugged into it. Is it possiblt to get a vacuum schematic for the car? Quote Link to comment Share on other sites More sharing options...
Canuck Posted December 13, 2010 Share Posted December 13, 2010 That is the TCS solenoid. Here is some info: http://arrc.epnet.com/autoapp/8977/8977CH04_Transmission_Controlled_Spark__.htm http://www.chevelles.com/forums/archive/index.php/t-1702.html Quote Link to comment Share on other sites More sharing options...
stangeba Posted December 13, 2010 Share Posted December 13, 2010 Good information. I think my TCS system came off on May 16th 1971. I remember some people complaining their vehicle took too much braking effort to slow down at highway speeds. I assume that's because the speed on the TCS was improperly adjusted higher than spec. The TCS system also energizes in reverse to allow you to properly adjust the "coast" idle speed. Good times! Bruce Quote Link to comment Share on other sites More sharing options...
Pauli Posted December 13, 2010 Share Posted December 13, 2010 A little off topic Bruce, but I turned 4 on 5/16/1971. Paul Good information. I think my TCS system came off on May 16th 1971. I remember some people complaining their vehicle took too much braking effort to slow down at highway speeds. I assume that's because the speed on the TCS was improperly adjusted higher than spec. The TCS system also energizes in reverse to allow you to properly adjust the "coast" idle speed. Good times! Bruce Quote Link to comment Share on other sites More sharing options...
cpmman Posted December 13, 2010 Author Share Posted December 13, 2010 Is it really needed? I have a 4 speed so not sure it makes a difference. Will the car perfrom okay without it? Quote Link to comment Share on other sites More sharing options...
stangeba Posted December 13, 2010 Share Posted December 13, 2010 Like I posted above, mine (71 350 4BBL 350 THM) came off years ago and it runs great. It was a way to meet emission standards by leaving the vacuum advance basically plugged till it shifted into third or on a 4 speed, 4th gear. Leaving it hooked up, may hurt power and economy some. How much, I don't know? Many of our 40 year old cars have been modified and repaired so much, I wonder if any work correctly. Paul, I turned 4 in 1957. Bruce Quote Link to comment Share on other sites More sharing options...
Canuck Posted December 13, 2010 Share Posted December 13, 2010 The TCS was missing off my 70 when I got it and it runs fine. I removed it from my 72 also. Quote Link to comment Share on other sites More sharing options...
MCfan Posted December 13, 2010 Share Posted December 13, 2010 Is it really needed? I have a 4 speed so not sure it makes a difference. Will the car perfrom okay without it? I discovered the TCS switch sticking out the side of my M20 last week when I was tightening loose shifter linkage. The spade connector and wire were missing and I had no idea what I was looking at. After consulting my Chasis Repair Manual and Googling "TCS switch", I learned more than I ever wanted to know about Transmission Controlled Spark. Talk about a Rube Goldberg invention! Looks like most of the original TCS system on my car has been missing since the Edelbrock manifold was installed in 1974. I suppose a perfectly restored car will have one that actually works, but it's looks like an unnecessary pain for just about everyone else. Quote Link to comment Share on other sites More sharing options...
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