papapete

I am going to change my distributor to a non ccc do you have any suggestions on a good after market? I have just had my q jet carb rebuilt
And plan on keeping it! Thanks

damoroso

If you’re running the stock carb, it’s controlled by the ECM too. Just changing out the distributor isn’t going to gain you much if anything. It would be helpful to know what mods if any your engine already has, and what you want to gain by swapping it out.

Richard Cooper

I believe you will have to change the carb too.

damoroso

You won't have to change the carb, but unless ther some done, there really isn't any gain in swapping the distributor.

LannyL81

You MUST change the carb if the CCC distributor is removed and a vacuum advance distributor is used. The stock E4ME carb will not work...well it will just will be a full rich on the primaries all the time.

Probably any Chevy QJet vacuum carb from a 350 SBC will work, easy and cheap to get one. New vacuum HEI distributors off of ebay are about $75.

But the real question is WHY....the CCC system works quite well actually...no performance reason to take it off unless major engine work has been done.

I put a higher lift cam in my '81 and did the small circuit addition to fool the MAP sensor so that it would not be sooooo rich at idle.

Are you having problems with the CCC?

Brians1

My 2 cents...keep the CCC distro. Works great with full CCC control. I just brought back my 81 to life after the PO gutted the CCC... ran like garbage, could smell it a mike away. Now back to CCC and she's running great

damoroso

What return signal does the distributor send the ECM for the carb's MC solenoid? I was under the impression that the ECM controlled, actually limited the advance, but there wasn't a signal FROM the distributor to the ECM. Also, I don't think there's a MAP on the 81's CCC. There's an ECM, a coolant sensor, a vacuum sensor, oxy sensor, TPS, TCC, air management system, TCC and the electronic spark timing function. Changing the distributor will set the check engine light but shouldn't send the mixture control solenoid full rich, or into the "limp home mode".

Brian and Lanny are right, when operating correctly, the CCC does a pretty good job and though not a power house, runs pretty well.

7T1vette

Computer fine-tunes the timing. And it adjusts the timing and fuel mixture based on throttle position, O2 sensor input, and other inputs. It also controls trans lockup function.

If you have all the components for the CCC system and they are functional, there is no reason to get rid of it. That system, when working properly, gets decent performance, very good mileage, and smooth idle and engine operation.

I'm sure there are ways to modify the CCC system to increase power/performance if you research a bit.

But if you want to scrub the CCC system, you will have to dump the computer, carb, distributor...plus you will have to replace the carb and dizzy and buy a lockup controller. Doesn't make financial sense to me when you will end up with "less".

P.S. I'm sure that you could change heads, cam and exhaust manifolds and still keep the CCC system operational.

Brians1

Exactly - all of the research I have done now for my 81, hypertech makes a chip for performance, new AFR heads, roller cam, ect and you have a bad beast, all with your CCC controlled carb ( q-jet 750cfm) it's a nice setup....about to purchase my AFR heads, etc and do the upgrade while keeping CCC fully in tact.

LannyL81

As 7T1Vette wrote: the ECM adjusts timing and fuel mixture of the primaries through inputs from the O2 sensor, coolant temp, TPS, plus a MAP sensor. Yep, the L81 engine has a MAP sensor. However it is not located on the engine, but instead on the firewall behind a cover.

I have a high lift cam and Edlebrock RPM Performer and Performer intake along with headers and using the CCC system. The engine does have low vacuum so I put a modification on the MAP so at idle the CCC did not think the engine was under load and thus set a richer idle mixture. Just this past weekend I found two vacuum leaks so I may be able t remove the mod...will not know for several months though as I am putting the car back together after a paint job.

But leave the CCC intact if possible. Rebuilding the E4ME carb is the same as any QJet although a couple of special tools are needed to set the mixture control solenoid, idle air bleed valve, etc. The FSM has all the instructions. Also join the L81 Vette Registry Forum - '81 owners only.

Good luck.

Brians1

LannyL81....What and where do I find "L81 Vette Registry Forum "??

papapete

Yes havering problems with ccc car runs fine till it gets warmed up(the first 4-5 miles) then it wants to load up serg then acts as if it is starving for fuel give it some gas it takes off then dose the whole thing over? It just won't curse at a steady speed?

Brians1

Here is what I had to do immediately after I purchased my 81:

New Items:
• plugs
• plug wires
• coil
• cap & rotor
• original 81 electric controlled Distro (got on e-bay) PO had a vacuum adv distro
• O2 sensor
• MAP sensor (it’s on FW next to dirsto under a cover)
• vacuum lines (several cracked to trans/lights/EFE sensor/vapor canister, etc.,)
• And this is the most important one - Properly rebuilt original Q-jet

All of the above combined and my issues that were very similar to yours - Gone
I also purchased a code scanner on e-bay for our year car. It’s called a "OTC Monitor 85" - I paid 10 bucks and its priceless for what I get - real time data for every CCC controlled item. Do yourself a favor and grab one.

this is my original thread on my journeys of getting my 81 operational and under full CCC control - lots of up and downs, maybe it will help you.
http://forums.corvetteforum.com/c3-t...ory-q-jet.html

damoroso

I think the MAP sensor being referred to is the vacuum sensor. I have a CCC distro from my 81 your welcome to if you need it.

LannyL81

Easiest way to find the L81 Corvette Registry Forum is to just Goggle L81 Corvette Registry...and the links show up.

papaete: from your description it sounds like when the ECM kicks-in and goes into closed loop mode is when the problem begins. Need to start at the beginning; condition of engine, plugs, wires, cap, rotor, check engine lite on ?, vacuum lines, O2 sensor, etc, etc.

What is the mixture solenoid dwell reading...is it varying or fixed? Have you checked for error codes?

Probably should start a new thread for troubleshooting this...but up to you.

papapete

I have about 63000 miles on the orginal motor all the numbers match,new cap,plugs,ECI. Have not replaced vacuum lines or map sensor. This problem was worse befor the carb rebuild. Will head in the vacuum direction next. Will keep everyone informed

LannyL81

How about the O2 sensor? Is the Check Engine lite on? Can you hear the mixture solenoid clicking? Checked the mixture solenoid dwell?

69427

Without the square wave reference signal (REF) from the distributor the ECM has no clue what RPM the engine is at, or where the crank and piston location is at any moment. Without that information the ECM can't control the spark timing.
MAP sensor is the correct description for the "vacuum sensor". It measures the absolute pressure (the AP in MAP sensor) in the intake manifold.

damoroso

Thanks for the clarification! I was looking for the MAP sensor in the service manual and it’s not mentioned anywhere, but there is a vacuum sensor, hence the question. Also, there appears to be only one lead from the ECM to the distributor, and I know it controls timing advance, the speed sensor is actually at the speedometer. So again, hence the question.

69427

There should be several wires between the distributor and the ECM. The Reference signal (dist to ECM), the EST signal (ECM to dist), the Bypass signal (ECM to dist) and IIRC, a ground line between the two parts.