Chevy Nova Forum

Chevy Nova Forum (https://www.stevesnovasite.com/forums/index.php)
-   Originality (https://www.stevesnovasite.com/forums/forumdisplay.php?f=47)
-   -   TCS Solenoid (https://www.stevesnovasite.com/forums/showthread.php?t=667265)

daddstoys71novas 7th-September-2019 12:28 PM

30 Attachment(s)
Car is 71 SS with the original 4 barrel quadrajet with 4 sp. Trying to install the TCS solenoid. I asked in the past about the wiring for it and got excellent advice but now it's the vacum lines for the solenoid. Assembly manual seems to cover it other than where it gets its vacum on the single side of the solenoid. The side with electrical connections. Pic is of original solenoid and bracket on the top with new one on the bottom. Original solenoid has one of the vac. lines broken off on the dual side. Also can't figure out where to mount the solenoid. Any advice would be appreciated.

SouthBay2s 8th-September-2019 10:36 PM

This is per older literature I have and is disclaimed to be generic.

--MOUNTING--
On the intake next to the carb OR on the carb top using one of the long corner housing bolts.

--VACUUM--
Single line to manifold vacuum off the carb body.

Double line side port to the distributor vacuum advance, possibly run through a TVS on the intake. The straight port to a clean air vent on the carb (possibly tee'd in with the clean air vent for the charcoal can).

YENKO DEUCE REG 10th-September-2019 07:42 PM

1 Attachment(s)
on the '70 Yenko Deuces they mount to a studded bolt on the intake manifold, it looks like this....

daddstoys71novas 10th-September-2019 09:01 PM

Thank you for the info gentlemen. I have been searching the web for info. and have come to the conclusion that my solenoid is for a 1970 chev as it has only vacum ports and that a 71 has an idle function on the single side of the solenoid. The pics in the assembly manual seem to support this but I could be wrong. Wouldn't be the first time. Which means the relays and the trans. solenoid are set for an idle as well as a vacum advance function. My solution is to wait until I have the motor running and see what the relays etc do. I still have to install the rebuilt M20 replace all the springs, rebuild the front suspension and put the original interior back and the list goes on.

YENKO DEUCE REG 11th-September-2019 09:36 AM

The TCS solenoid for '70 is a '432' unit, as stamped on the bracket. As I recall, there are 2 vacuum ports on one end, and only one port on the other end along with a 2 wire plug.

The TCS (Temperature Controlled Spark) system is not functionally required, in fact, from a performance standpoint you're better off without it! Many of us simply drill through the solenoid to disable it, or route the vacuum lines in a way so that it appears to be hooked up when in fact it is not (that's what I've done on my Yenko). Essentially, the TCS system prevents full vacuum advance until the engine is at operating temp and the transmission is in 4th gear = yawn....

SouthBay2s 11th-September-2019 11:00 AM

Quote:

Originally Posted by daddstoys71novas (Post 5849051)
Thank you for the info gentlemen. I have been searching the web for info. and have come to the conclusion that my solenoid is for a 1970 chev as it has only vacum ports and that a 71 has an idle function on the single side of the solenoid.

One of my reference sources supports this, another does not. It could be somewhere in the middle, where the unit becomes a type of idle stop solenoid in 1971, but only for California. That was a common practice across car makers in this period.

When you are ready to put this thing back together, PM me and I will send you scans of what literature I have.

As for disabling it, you could use small BBs or break off golf tees inside the vacuum lines. That is an old trick to beat the California step #1 visual test.

From reading an overview of the 1971 system, it is there to prevent dieseling, delay spark advance at certain times and the big one appears to be cut spark advance on WOT decel. Yours uses both a temp sensor and TVS, so it would only operate in certain engine temp ranges. It would be a fun little project to try and get it to actually work. All that bolt on stuff was rushed engineered to meet new Federal emissions regs and often only functioned correctly on paper.

AZ71 23rd-September-2019 07:07 PM

The 1971 system is unique. For 1971, the TCS was replaced by the Combined Emissions Control (CEC) Solenoid. Several other components exist in the system including Cold Override Temperature Switch on the cylinder block, a Time Delay Relay, Reversing Relay and Transmission switch. The 2 relays are mounted on the firewall. Unless all these components are there and working, just replacing the solenoid won't work.

Note that most diagrams in the assembly manuals and wiring diagrams still referred to TCS. The Time Delay Relay and Reversing Relay are shown on the assembly manual sheets 7A-4 and 12-12 &13 and called TCS relays.

I am the original owner of my 71 Nova. The CEC system had not been messed with, but the 2 relays had failed. I was able to replace them with NOS parts, and the car runs much better. No more dieseling and stalling.

Of course, many people just try to rip out the emissions systems and do without them on an old car.

A 1971 CEC manual can be purchased on ebay. Item 183786038581.

It explains how the system works, and how to troubleshoot it.

There is also a TCS repair guide on the Autozone website that might help.

YENKO DEUCE REG 24th-September-2019 10:09 AM

Quote:

Originally Posted by AZ71 (Post 5851211)
The 1971 system is unique. For 1971, the TCS was replaced by the Combined Emissions Control (CEC) Solenoid. Several other components exist in the system including Cold Override Temperature Switch on the cylinder block, a Time Delay Relay, Reversing Relay and Transmission switch. The 2 relays are mounted on the firewall. Unless all these components are there and working, just replacing the solenoid won't work.

Note that most diagrams in the assembly manuals and wiring diagrams still referred to TCS. The Time Delay Relay and Reversing Relay are shown on the assembly manual sheets 7A-4 and 12-12 &13 and called TCS relays.

I am the original owner of my 71 Nova. The CEC system had not been messed with, but the 2 relays had failed. I was able to replace them with NOS parts, and the car runs much better. No more dieseling and stalling.

Of course, many people just try to rip out the emissions systems and do without them on an old car.

A 1971 CEC manual can be purchased on ebay. Item 183786038581.

It explains how the system works, and how to troubleshoot it.

There is also a TCS repair guide on the Autozone website that might help.

Thanks, this is good to know - I presumed the '71 was similar to the '70, but it sounds like it's much more complicated!


All times are GMT -4. The time now is 07:26 PM.

Powered by vBulletin® Copyright ©2000 - 2019, Jelsoft Enterprises Lt
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.


Garage Plus vBulletin Plugins by Drive Thru Online, Inc.