I'm starting to do some Fall maintenance and while exploring the wiring diagram I had some questions concerning the CCC...

My car has a 4 year old 350 crate motor in it and when it was installed by the previous owner, the CCC was unplugged. This is all the information I have concerning this component.

My question is this... what effect does this have on the functioning of the car?

I have a wiring diagram and I see lots of inputs, which I assume are benign at this point, but what were the outputs and what did they control?

I thought I read that it had some control over the distributor and the carb - if that is the case, how are those two devices functioning now that the CCC is no longer sending them inputs?

I also see in the wiring diagram that the CCC was connected to the O2 sensor, idle stop sol, fuel meter sol, air inj sol - what effect did the CCC have on these components?

Finally I see it is connected to a bunch of relays - Air Sw RLY, TCC and EGR Bleed Rly, EGR Bleed control sol, TCC sol, and EGR sol. Do these functions just not exist with my new (modern ~2008) engine?

Can anyone explain this in some detail - I was just curious how my car even runs with this thing disconnected. :-)

Thanks for any info.

 

You would have to post a picture of your engine with sufficient detail to see what carburetor and intake manifold you have and what distributor you have. If the previous owner installed non-computerized components there no longer is any need for the CCC.

 

Take a look at the plug going into the distributor, if it has a huge 4 wire plug and no vacuum advance can it is the original, if not and it has a small plug AND a vacuum advance can with a vacuum hose to it, it has been replaced. Look at the carb, if it has any electrical connections other than the choke, or if it is a Holley or Edelbrock it is NOT original. If those are changed and the ECU is unplugged, drive it. The Lockup on the tranny may not work, but thats no big deal. All of the other sensors need not be there if the carb and dist have been replaced since all of those are only inputs to control mainly the mix on the carb. BUT.....a computer controlled 81 with a bad or unpplugged ECU will still run, and not run too bad. It will be in an extremely rich mode and will get horrible gas mileage. I suspect the carb and dizzy were replaced with the motor. The lockup on a stock TH350C tranny is after third gear it will lockup the converter for a 1-1 drive and drop the RPM's 3-400 giving you a lower RPM and a tad better highway mileage. There is not a lot more to explain. Good Luck.

 

If you have a copy of the Chevrolet Chassis Service Manual for 1981 (you should have one, anyway, if you do any work on your car), just read about the CCC system in that manual. That manual will also have testing and diagnostic info for each component in that system.

Originally, the '81 C3 had the first computerized engine management system used in a Corvette. It consisted of unique carb [with solenoid operated fuel mixture control], unique distributor, ECM unit, oxygen sensor, and an interconnecting wiring harness with inputs from other engine sensors. Considering that it controlled a carburetor, it worked pretty well; but it was only an interim system until throttle body fuel units were installed the following year.

If you have a replacement engine and no longer have the carb and dizzy from the original engine, it would be costly and troublesome to find the parts to "re-engineer" your present engine.

 

With the possibility of repeating what has already been said.

The only thing that has to be done to remove the CCC from an 81 is to replace the carb and the Distributor. As has already been said, the computer will also lock up the converter. If the carb and distributor have been replaced, the car does not need the ECM at all. It is not at all unusual that someone putting in a crate motor would make the transition.
The distributor would probably be replaced with a vacuum distributor. The 81 will have no vacuum diaphragm and have the 4 pin connector.

The 81 carb will have a connector on top of the carb, and one in the front. If they are not there it is not an 81 carb.

Good luck

 

Thanks everyone for the excellent info.

I only had a few minutes this afternoon, so the pics I took were without removing the all of the components to get a clear view of the carb - if we need more detail, I can try to take some better ones next week.

I do actually get pretty bad mileage - like 12-13 city and highway. Maybe that's normal for one of these, but I would think with a 3-4 year old crate motor, it could do a little better than that. :-)

I have also replaced the original 3 speed auto with a TKO500 5 speed manual - excellent conversion and highly recommended for those in a similar situation. So in terms of the transmission, the CCC is a non-issue for me.

Can anyone tell from my basic pics which carb and distributor I have?

A question comes to mind... since 81 was the first year for the CCC, and since the previous owner put in a crate motor and ditched the CCC, would a carb and a dist from and 80 work without modification in my 81? If this is the case, what other years would also work out of the box?

http://www.flickr.com/photos/8756156...in/photostream

http://www.flickr.com/photos/8756156...in/photostream

http://www.flickr.com/photos/8756156...in/photostream

http://www.flickr.com/photos/8756156...in/photostream

 

just for the record the '81 was not the first and only year of the CCC. The CCC system was first introduced in '80 but only for the California edition 305 cid cars.

Here is a picture of my spare CCC system carb. Note the blue connector on the top of the carb is the mixture control solenoid the white connector in the front is the throttle position sensor.


I hope this helps you.

 

Both the distributor and the carb are NOT 81 ccc. The car has been set up without the computer.