1981 Rochester Quad
Thread Starter
Heel & Toe
Joined: Apr 2011
Posts: 19
Likes: 0
From: Waxahachie Texas
1981 Rochester Quad
My 1981 has a Holley without proper EGR stuff so I bought a proper QJet. It is for the auto which I have. Also got a kit.
Before I get started is there anything I need to know? I saw the thread below this one.
Thanks in advance.
Before I get started is there anything I need to know? I saw the thread below this one.
Thanks in advance.
Racer
Joined: Feb 2007
Posts: 290
Likes: 0
From: Winchester CA
Have you rebuilt carburetors before? Take your time with it and go about it methodically. Make sure everything is hospital clean as you go along with the rebuild. Safety safety safety always when handling anything to do with gasoline.
Race Director
Joined: Sep 2002
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From: San Diego - Deep Within The State of CONFUSION!
Le Mans Master
Joined: Oct 2010
Posts: 6,930
Likes: 842
From: melbourne florida
2023 C3 of the Year Finalist - Modified
he is likely not running the compute beacause it has a Holley on it now. a quadrajet is a decent Carb if, if it's built properly if it is fine tuned for the car and fuel and if I'd gets no dirt in it to clog a passage and if the bottom plugs don't leak and if the throttle shafts stay tight and if the top doesn't warp. it is an o.k. Carb but when you guys are in the garage working on your carburetor, I'm out driving mine. you can have your choice i made mine long ago
Drifting
Joined: Aug 2009
Posts: 1,635
Likes: 8
From: Enid Oklahoma
he is likely not running the compute beacause it has a Holley on it now. a quadrajet is a decent Carb if, if it's built properly if it is fine tuned for the car and fuel and if I'd gets no dirt in it to clog a passage and if the bottom plugs don't leak and if the throttle shafts stay tight and if the top doesn't warp. it is an o.k. Carb but when you guys are in the garage working on your carburetor, I'm out driving mine. you can have your choice i made mine long ago
Thread Starter
Heel & Toe
Joined: Apr 2011
Posts: 19
Likes: 0
From: Waxahachie Texas
Yeah, the problem is that the state (Colorado) wants the carb running on the computer. It has a new Holley that doesn't make the connection.
Can't see the car right now because I'm in Texas for a while. The Holley was put on by a Denver Corvette guy who's done a good job otherwise. The original Q-jet is gone.
Thanks for the help.
Can't see the car right now because I'm in Texas for a while. The Holley was put on by a Denver Corvette guy who's done a good job otherwise. The original Q-jet is gone.
Thanks for the help.
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Instructor
Joined: Aug 2010
Posts: 233
Likes: 18
From: Monrovia Md
If it is really an 81 Qjet (E4ME) for a corvette it will need the ECM to run properly. You can tell if it is an 81 Qjet because it will have two electrical connectors, one on the top passenger side (mixture solenoid) and one on the front drivers side (Throttle Position Sensor).
If it is an E4ME, it will not run correctly unless the ECM is running correctly. Since it was replaced with a Holley, I would guess that all the other stuff has been disconnected or neglected. If you are not getting a check engine light, the computer has been disabled, removed, or the lightbulb has been removed.
Getting the 81 to work with the original carb and ECM is not an impossible task, but it may be more complex than just putting a carb on it. Let me know if that is the direction you want to go and we can begin to figure out how far the 81 is bubba'd up.
If it is an E4ME, it will not run correctly unless the ECM is running correctly. Since it was replaced with a Holley, I would guess that all the other stuff has been disconnected or neglected. If you are not getting a check engine light, the computer has been disabled, removed, or the lightbulb has been removed.
Getting the 81 to work with the original carb and ECM is not an impossible task, but it may be more complex than just putting a carb on it. Let me know if that is the direction you want to go and we can begin to figure out how far the 81 is bubba'd up.
Burning Brakes
Joined: May 2008
Posts: 1,116
Likes: 5
From: Middleburg Florida
Not only does it need the ECM to operate properly, it needs the O2 sensor, and the Manifold Pressure Sensor too. The ECM also controls spark advance, so you'll need the CCC distributor if yours isn't the stock unit. If you don't have a "Check Engine" light with the Holley, chances are either the ECM is gone, disconnected, or the bulb has been pulled out of the center cluster.
Both Cliff and Doug's books are very good, but the 81 service manual has an excellent section on rebuilding the carb too.
Both Cliff and Doug's books are very good, but the 81 service manual has an excellent section on rebuilding the carb too.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
Some good advice in here, some not so much. The E4ME as stated by some is an excellent carb. It is a little complicated but its not like a flux capacitor. Dougs book is an excellent source. While your rebuilding and getting the E4ME setup corectly you need to also make sure all the other CCC system components are in place and working correctly. The Distributor is special, there is no vac advance and it has a 4 wire plug for the computer, there is an O2 sensor in the drivers side exhaust, it sontrols the timing and fuel air mix on the carb. There are a Vac sensor and atmospheric sensors on the firewall and a connectin on the tranny and one on the speedo. If you get all that working the carb will perform very well. You can also do some pretty hefty mods and the CCC and Carb will support them. Dual exhaust, bumpier cam, better heads and a overdirve tranny are all possible with very little tweaking.
Instructor
Joined: Aug 2010
Posts: 233
Likes: 18
From: Monrovia Md
Be glad to help you when you get back -- It can be done!
First thing you should do is to buy the 1981 service manual -- it has an excellent section on the computer control system, all of its components and its operations.
Good luck!!
First thing you should do is to buy the 1981 service manual -- it has an excellent section on the computer control system, all of its components and its operations.
Good luck!!
Instructor
Joined: Apr 2011
Posts: 137
Likes: 0
From: Goose Creek SC
wajulia, I believe I have a bubba'd-up '81. The computer is gone. My Check Engine Light comes on once the engine is warmed up. How can I tell if I have the stock HEI Distributor? Based on your E4ME description, that is what I have and it does run poorly. I recently purchased the car and the owner didn't know much about the car, he only owned it for about 6 months. Thanks in advance.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
The '81 has a 'unique' carb with an electronically managed fuel mixture controller, a 'unique' distributor which sent timing info to the computer, an oxygen sensor, an ECU which played the part of the "brain" of that system, and a 'one-year-only' electrical harness with temp sensor and throttle position sensor inputs (if I remember correctly). All the right parts need to be in place and operational for the system to work at all. Otherwise, the computer just runs in an "open-loop" program which runs, but not well.
So, if you don't really want to find all the missing parts and reconnect everything, you should swap out any of the 'unique' components and just go back to the "good ol' days" of a carb and a distributor [not those off the '81, as they won't work properly without the whole system].
If you have all the correct components, the '81 engine control system would be an improvement to the prior vintage systems. But, you have to make that call. Good luck with it.
So, if you don't really want to find all the missing parts and reconnect everything, you should swap out any of the 'unique' components and just go back to the "good ol' days" of a carb and a distributor [not those off the '81, as they won't work properly without the whole system].
If you have all the correct components, the '81 engine control system would be an improvement to the prior vintage systems. But, you have to make that call. Good luck with it.
C3 Corvette Enthusiast
Joined: May 2008
Posts: 1,071
Likes: 3
Yeah, the problem is that the state (Colorado) wants the carb running on the computer. It has a new Holley that doesn't make the connection.
Can't see the car right now because I'm in Texas for a while. The Holley was put on by a Denver Corvette guy who's done a good job otherwise. The original Q-jet is gone.
Thanks for the help.
Can't see the car right now because I'm in Texas for a while. The Holley was put on by a Denver Corvette guy who's done a good job otherwise. The original Q-jet is gone.
Thanks for the help.
These guys look for stuff to fail cars. They almost failed the car because the cats weren't getting hot enough for their liking. I'm hearing horror stories from people who have relatively new cars that are failing because of some ******** reason.
I'm seeing a lot of muscle cars popping up on Craigslist because they don't have all of the emissions equiptment that came with the car. Good luck to you in passing your car and not getting buttraped by these "emissions inspectors".
Instructor
Joined: Aug 2010
Posts: 233
Likes: 18
From: Monrovia Md
wajulia, I believe I have a bubba'd-up '81. The computer is gone. My Check Engine Light comes on once the engine is warmed up. How can I tell if I have the stock HEI Distributor? Based on your E4ME description, that is what I have and it does run poorly. I recently purchased the car and the owner didn't know much about the car, he only owned it for about 6 months. Thanks in advance.
For the Distributor -- it will NOT have a vacuum advance on it and will have a flat four wire connector coming out the drivers side. The connector will be about 2inch square with 4 wires in it.
If you think that you have the carb and distributer I can send you process to read the error codes out of the computer and we can begin from there. Maybe all the stuff is still there. Can you give me a picuture of the engine, without the air cleaner from both sides -- I could tell you how much I see missing.
Good luck
Thread Starter
Heel & Toe
Joined: Apr 2011
Posts: 19
Likes: 0
From: Waxahachie Texas
I'm in Texas for a while and the Corvette is in Colorado in storage but when I get back I hope to take advantage of your offer.
I did get another quadrajet with all the proper numbers and connections and a kit from e-bay so I'm hoping for the best. Thanks.
I did get another quadrajet with all the proper numbers and connections and a kit from e-bay so I'm hoping for the best. Thanks.
Instructor
Joined: Apr 2011
Posts: 137
Likes: 0
From: Goose Creek SC
First -- if the check engine light comes on the computer is not gone. It is in the compartment with the battery behind the drivers seat, tucked away on the side towards the drivers seat. It is a rectangular silver box with two connectors coming out of one side. This means that we can start to get codes out of it to see what it sees as missing. This will do you no good until you get an E4ME carb and a computer controlled Distributor
For the Distributor -- it will NOT have a vacuum advance on it and will have a flat four wire connector coming out the drivers side. The connector will be about 2inch square with 4 wires in it.
If you think that you have the carb and distributer I can send you process to read the error codes out of the computer and we can begin from there. Maybe all the stuff is still there. Can you give me a picuture of the engine, without the air cleaner from both sides -- I could tell you how much I see missing.
Good luck
For the Distributor -- it will NOT have a vacuum advance on it and will have a flat four wire connector coming out the drivers side. The connector will be about 2inch square with 4 wires in it.
If you think that you have the carb and distributer I can send you process to read the error codes out of the computer and we can begin from there. Maybe all the stuff is still there. Can you give me a picuture of the engine, without the air cleaner from both sides -- I could tell you how much I see missing.
Good luck