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Topic: smog removal

in Forum: C3 Fuel, Emission Control, and Exhaust Systems

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smog removal (1/5)
8/5/15 1:36pm

shelly 81
Former Member
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Saint Charles, MO - USA

Vette(s):
1981 dark blue metalic St.Louis built.

Joined: 11/20/2007
Posts: 4

I want to remove the emission devises and computer from my 81(non ca). I have HEI. I don't know any thing about the connector on the carb and don't want to tear into it till I get info on it. I know that the computer controls metering and timing (every 10 sec., WOW). I have a wiring and vacuum diagram, I just want good advise on how to attack it before I start. As far as eco and mpg, I've had her 9 and a half years and put 5000 miles on her verified 52001.3 total miles. Any help would be great! Thanks!

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Re: smog removal (2/5)
8/5/15 2:40pm

johnu
Standard Member
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Scottsdale, AZ - USA

Vette(s):
1981 Corvette Two-Tone Claret color, 4 spd, C7 Vert

Joined: 5/23/2007
Posts: 614

I'm probably wrong... but why bother for 600 miles a year? The gains from that low-hp motor might be too small to feel. I chose to keep my '81 stock and eliminate any headaches trying to reinvent this motor. Plan A would be to do the full monte like Sarge81 did to his with the proper fuel injected motor.

|UPDATED|8/5/2015 11:40:08 AM (AZT)|/UPDATED|

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Only 32 years together

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Re: smog removal (3/5)
8/5/15 4:02pm

Sarge81

Lifetime Member
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WEST SENECA, NY - USA

Vette(s):
1981 Blue Ice Met. w/pearl ghost flames TKO500 5speed. LS1 Swap 3.45 Dana 44.

Joined: 12/3/2001
Posts: 2379

If the system is becoming troublesome such as mine originally was. Just yank that engine out and either put some higher compression pistons, heads and a mild cam in it or put a crate engine in it. The stock pistons are only 8.2:1 CR. So no matter what you do with it in stock form you won't get significant power gains.

I put a GM 350 HO crate engine in it back about 13 years ago. Stripped out ever bit of computer wiring and computer. Went with a non computerized Qjet carb and HEI distributor. There was one green wire that connected near the wiper motor. It was part of the computer wiring. That had to stay otherwise the A/C would't kick on.

Last year I went the "full monte" as John mentioned. I shoehorned a Gen III LS engine into my car. Basically its built to a '02-'04 spec Z06 engine with a step over stock on the cam. Runs like a modern vette now.

Is your car a automatic or manual transmission?

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GEN III 5.7L "LS6" Engine swap
TKO500 5 spd.

3.54 Dana 44

'69 "N11" Sidepipes
Borgeson Steering Box
Born 8/1981
Sequence #3975

Click here to see more pics of my Vette on CarDomain.

Lifetime Member #26

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Re: smog removal (4/5)
8/5/15 4:33pm

kstyer

Lifetime Member
Moderator
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CUYAHOGA FALLS, OH - USA

Vette(s):
1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!

Joined: 12/2/2003
Posts: 6424

If the car is not causing problems, I agree, why bother? BUT if you still wish to do so, it's really easy.

Replace the carb with a non electronic controlled qudrajet carb. The hook ups will be the same minus wiring connections. Replace the distributor with a standard HEI from 80 or older, and connect the vacuum line, tach lead, and power lead. Unplug the ECM.

Done.

If you want to you can also disconnect the EGR, but you may have some pinging problems. You can disconnect the AIR (air pump) system simply by removing it, and pluging the lines into the exhaust manifold. The EFE, Early Fuel Evaporation, is a vacuum controlled heat riser. If it's not causing a problem, leave it alone. It will help the engine warm up faster.

|UPDATED|8/5/2015 1:33:28 PM (AZT)|/UPDATED|

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Re: smog removal (5/5)
8/6/15 10:09am

shelly 81
Former Member
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Saint Charles, MO - USA

Vette(s):
1981 dark blue metalic St.Louis built.

Joined: 11/20/2007
Posts: 4

Great responses. The reason I even thought about it is that I need to rebuild the carb and was going to tear out the smog crap. So i'm going to leave her alone and just fix the q jet. I've rebuilt q-jets before but it's been a while so any tips on that would be appreciated! I've also purchased an aluminum radiator for the old girl and plan to use Water Wetter. I've heard two bottles is best, but what about the coolant? Is there a better than recommended product to help cool her? Again, great advise! Might put 700 miles on her this year.

SAVE THE WAVE! Big smile

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