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Old 02-26-2016, 07:29 PM
paulywood paulywood is offline
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I identified the relay. It's not the horn relay, it's the T.C.S relay. Does anyone know what that is/does?
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Old 02-26-2016, 11:45 PM
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chevymaher chevymaher is offline
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Smog device to retard timing.
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Old 02-27-2016, 11:07 AM
paulywood paulywood is offline
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Thanks for the help guys. I'm going to upgrade to a new alternator so that takes care of the voltage regulator and don't need a horn relay, there's one included in my wiring kit that mounts under the dash. Just not sure about the T.C.S. relay.
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Old 02-28-2016, 09:35 AM
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I borrowed this from other posts, so Here are a couple of comments I found

TCS=transmission controlled spark. This was a 1970 Emissions idea. The whole idea was give the engine advanced timing (via vacuum advance to the distributor) when it was only really needed, therefore reducing exhaust emissions. The TCS relay is a small relay box that is riveted to the wiring gutter that runs under the hood close to the top of the cowl, you know the one that carries the wire with fuse to the a/c/heater blower.

The TCS solenoid (sol) mounts on the passenger side of the intake manifold by the distributor. It is metallic colored and has 3 wire connector One goes to the carb base (vacuum) one goes to the distributor vacuum advance nipple, one goes to the top of the carb (clean air, no vacuum). A wire runs from your tranny to the relay.

The theory was

When the car is in any gear but drive, the small switch that is in the side of the tranny is not activated (not grounded), when you put the car in drive ( I guess 3rd or 4th with a stick shift) the tranny fluid puts pressure on the switch activating it and grounding the circuit that goes to the relay, this causes another circuit to trip that sends 12 volts via the blue and black wire with flat plug to the solenoid on the manifold, It triggers it to let full vacuum from the carb to the vacuum advance on the distributor.

The original GM relay is still availibe through Year One, OPG, or many other m/o houses. I haven't seen a solenoid for sale commerically until recently.

I believe you can get reproduction TCS solenoids from Ground Up:

another post

I've played with the idea of installing this item. What benefits are there to re-installing this system. Will it hurt performance?

If you just want a good cruiser then don't do it, there is no advantage. It will only hurt performance a little but it definately does not help. To correctly hook it all up and FIND all the correct parts would be a major effort.
By the way the TCS temp sensor that has two lugs on it: one is for low temp and one is for high. Like Coppertop stated this overides the solenoid when its "COLD"(<85deg) and also when "HOT" (>220deg).

This system was one of GMs typical stop-gap, Rube Goldberg deals to meet pollution laws back then. I had a couple cars with this and usually removed it about the second day I had it. Only advantage I can see is the timing retard makes the engine idle a little "meaner" with a big cam. The best vacuuum set up is to use ported vacuum with the connection above the throttle plates which will give advance when the throttle is opened partially. If you have cooling problems in town the manifold vacuum might be the best with full time advance except at wide open throttle. tom
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Old 03-05-2016, 04:02 PM
paulywood paulywood is offline
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I talked to one of the reps at American Autowire and he also said I didn't need it. Thanks for the help guys. I should be able to button up the engine bay wiring next weekend when I'm feeling better.
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