81 Vette smog carb


Old 08-05-15, 10:05 AM
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81 Vette smog carb

I want to remove the smog devices on my 81 C3 Corvette. She does have an HEI distributor. The quadro jet carb has a connector that I don't know about and I don't want to tear into it until I get info. I basically want to eliminate the smog devices and computer (which only controls the metering and timing). As far as eco and mpg is concerned, I have owned her for 9 and a half years and put a hole 5000 miles on her, I verified that the 52001.3 miles on her are true. Any help would be amazing. Thanks!
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Old 08-05-15, 12:02 PM
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As much as I am a purist when it comes to older cars, the newer ones have pollution devices that are placed there for a reason. Circumventing those reasons is first, illegal, and second will degrade the performance of the car in time. I don't think such advice would be in the interest of the forum. Others may have different ideas, so let's see where it takes us.
Old 08-05-15, 12:33 PM
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I cannot reply directly to your situation, but do recall that a lot of cars in that era did not respond well to simply removing the emission equipment, and that a lot of it consequently was reinstalled in order to maintain some manner of reliability. Bigger issues than an air pump, EGR system, etc. were the reduced compression, leaner carburetors, reduced and/or limited spark advance, etc. So, not advocating to not do it, but, unless you are planning to replace the heads, intake manifold, carburetor, probably exhaust manifolds, distributor, etc., I think that you might be quite disappointed.
Old 08-05-15, 02:35 PM
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removing emission devices usually results in less performance and fuel mileage. And 81 may have just bolted on devices but can't remember.
Old 08-05-15, 10:42 PM
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I've dealt with quite a bit of this kind of thing and yes it's possible to eliminate most of the emission components while simplifying things. You really need to use an earlier QJ carburetor with no electronic controls or an aftermarket carb such as an Edelbrock.
The HEI distributor would need to be replaced with an HEI unit with a vacuum advance on it and the catalytic converters would need to be gutted if this model uses a secondary air injection system; or air pump which I assume would also be removed.

One thing you must leave place is the EGR valve. The EGR lowers combustion chamber temps and controls pinging. No EGR or an inoperative EGR can be engine damaging if pinging is allowed to continue.

I don't know the limit of your expertise on working around things like this so I can't speak for the difficulty involved. To me, doing something like this is not that difficult but to be honest, if the Vette were mine I'd probably leave it alone as I'm a stickler for originality.
That body style is the last of the "real Vettes" in my opinion. In 1984 they tanked...... :-(
Old 08-06-15, 07:18 AM
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Thanks to all. I was also on a Vette forum and the advise was the same- If it ain't broke done fix it! Just gonna do a stoke rebuild on the Q-jet and keep crusin'. Thanks again!

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