Resurrecting an old 1981
Thread Starter
Cruising
Joined: Feb 2024
Posts: 14
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Resurrecting an old 1981
New member addressing an abused 1981 base model. Found this Corvette that has been through many hands over the last 40 years. There are many things that don't work, from driver's door window through inop gauges etc. Someone replaced the electronic Quadrajet with a more basic carb and the electronic ignition with an HEI distributor. While the engine runs fine above idle the transition from idle to accelerating is marked with a stumble. I plan on rebuilding the carb next weekend but am curious about the impact the HEI may, or may not, be having on the tach. The tach needle bounces around and is seldom steady jumping from 2000 to 3000 RPM at steady throttle. Speedometer seems to have become infected as well. Any insight would be appreciated.
Race Director
Joined: Mar 2017
Posts: 11,934
Likes: 4,497
From: Virginia
Sounds like you have a neglected car that has many separate, but hopefully minor, issues. The good news is that someone likely eliminated the computer controlled carb (CCC), ECU, and 81-specific distributor.
Speedo: Could be as simple as a new speedo cable. Is there a (likely non-functional) cruise control module? You can bypass that, and home-run a new non-cruise speedo cable.
Tach: Tach board. Perhaps @interpon will post his thread on this.
HEI: It's not an HEI issue, but there is also a tach filter that may be missing or need to be replaced.
Carb rebuild? Probably. But is there an adaptor under the carb to convert from a 4 equal bore (Holley 4-barrel style) carb to a spread bore (Quadrajet style) intake? If so, you'll never get the car to run correctly until you address this.
Please post some photos!
Speedo: Could be as simple as a new speedo cable. Is there a (likely non-functional) cruise control module? You can bypass that, and home-run a new non-cruise speedo cable.
Tach: Tach board. Perhaps @interpon will post his thread on this.
HEI: It's not an HEI issue, but there is also a tach filter that may be missing or need to be replaced.
Carb rebuild? Probably. But is there an adaptor under the carb to convert from a 4 equal bore (Holley 4-barrel style) carb to a spread bore (Quadrajet style) intake? If so, you'll never get the car to run correctly until you address this.
Please post some photos!
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Very optimistic n my opinion. I would spend some money on a mechanic that knows C3's and he should be able to point out what is needs to fixed and what can wait. Good luck to you.
Le Mans Master
Joined: May 2007
Posts: 5,021
Likes: 1,120
From: North tonawanda NY
I would pass for young 81 instead... In all seriousness I mean there arena whole lot of c3 corvettes younger than an 81... just saying. if you want an 81 corvette there are many many better options. If you want a c3 corvette you plan on modifying heavily to make it perform better than an 81 you have good option. in front of you. The point is in my opinion that the 81 was in its stock form not great.... and it sounds like the things you might need to address were because other already tried to start addressing those faults and may not have done it correctly.
Last edited by augiedoggy; Mar 17, 2024 at 06:14 PM.
