81 distributor
Thread Starter
Intermediate
Joined: Feb 2013
Posts: 33
Likes: 0
From: Lake Placid Florida
81 distributor
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
And plan on keeping it! Thanks
Burning Brakes
Joined: May 2008
Posts: 1,116
Likes: 5
From: Middleburg Florida
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.
Melting Slicks
Joined: Nov 2005
Posts: 3,323
Likes: 142
From: Green Valley Arizona
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?
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?
Burning Brakes
Joined: Nov 2013
Posts: 889
Likes: 13
From: Jax/St. Augustine FL
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
Burning Brakes
Joined: May 2008
Posts: 1,116
Likes: 5
From: Middleburg Florida
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?
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?
Brian and Lanny are right, when operating correctly, the CCC does a pretty good job and though not a power house, runs pretty well.
Last edited by damoroso; Jan 15, 2014 at 12:03 AM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
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.
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.
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Burning Brakes
Joined: Nov 2013
Posts: 889
Likes: 13
From: Jax/St. Augustine FL
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.
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.
Melting Slicks
Joined: Nov 2005
Posts: 3,323
Likes: 142
From: Green Valley Arizona
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.
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.
Burning Brakes
Joined: Nov 2013
Posts: 889
Likes: 13
From: Jax/St. Augustine FL
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.
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.
Thread Starter
Intermediate
Joined: Feb 2013
Posts: 33
Likes: 0
From: Lake Placid Florida
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?
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?
Burning Brakes
Joined: Nov 2013
Posts: 889
Likes: 13
From: Jax/St. Augustine FL
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
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
Melting Slicks
Joined: Nov 2005
Posts: 3,323
Likes: 142
From: Green Valley Arizona
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.
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.
Last edited by LannyL81; Jan 16, 2014 at 07:02 AM.
Thread Starter
Intermediate
Joined: Feb 2013
Posts: 33
Likes: 0
From: Lake Placid Florida
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.
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.
Tech Contributor
Joined: Jun 2004
Posts: 20,847
Likes: 959
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
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.
Brian and Lanny are right, when operating correctly, the CCC does a pretty good job and though not a power house, runs pretty well.
MAP sensor is the correct description for the "vacuum sensor". It measures the absolute pressure (the AP in MAP sensor) in the intake manifold.
Burning Brakes
Joined: May 2008
Posts: 1,116
Likes: 5
From: Middleburg Florida
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.
MAP sensor is the correct description for the "vacuum sensor". It measures the absolute pressure (the AP in MAP sensor) in the intake manifold.
Tech Contributor
Joined: Jun 2004
Posts: 20,847
Likes: 959
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
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.