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Topic: Re: BLOWS BLACK SOOT

in Forum: C3 Engines


Re: BLOWS BLACK SOOT

Posted: 12/18/16 4:58pm Message 11 of 18
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Duncanville, TX - USA
Joined: 11/8/2003
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
ECM only controls the idle fuel mixture and the ignition timing....nothing else. I would suggest getting the codes, and see what the ECM has for info on the problem. It is definitely a carb problem. Perhaps it was running fine when it left Fla., but bouncing on a transport could have caused a problem.


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Re: BLOWS BLACK SOOT

Posted: 12/19/16 7:18pm Message 12 of 18
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deforest, WI - USA
Joined: 12/14/2016
Posts: 13
Vette(s): 1981 work in progress
I pulled the #8 & # 6 plugs today and they had the same soot as I'm blowing out the exhaust  so I'm really hating to think that the carb was not replaced but fixed to stop it from stalling so more questions do I try and find another shop or send it to a rebuilt facility which all they do is rebuild Q-jets all day or buy a new one or replace it with a bigger and better compatible one don't want to reinvent the wheel I want a plug and play any ideas


Re: BLOWS BLACK SOOT

Posted: 12/19/16 10:42pm Message 13 of 18
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Overland Park, KS - USA
Joined: 7/9/2003
Posts: 914
Vette(s): 1973 Orange Metallic Coupe (orig owner), L82, 4 spd (WR), PS, (A/C & PW (I installed from wrecked 73)), leather, AM/FM Stereo, ran with '65 FI unit earlier & will again some day. 2023 Accelerate Yellow HTC Stingray
Get a Q-jet repair kit and rebuild it yourself. If they truly didn't give you a new carb, then I would get a new float also. You don't need a bigger carb. IIRC, the Q-jet is good to at least 700 CFM.


1973 L-82 4 spd

Re: BLOWS BLACK SOOT

Posted: 12/20/16 2:45pm Message 14 of 18
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Flanders, NJ - USA
Joined: 1/27/2004
Posts: 2556
Vette(s): 1982 Black, ZZ4, Hooker Side Pipes, 3.55 Rear, Rebuilt & upgraded 700R4, All new suspension, brakes, & new Charcoal interior.
You said you were going to get rid of the O2 sensor? Can't do that if you keep the 81 carb. The computer needs it.
That black smoke is a fuel issue for sure, way too rich.
Hope you get it sorted out.
Dave



 

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Re: BLOWS BLACK SOOT

Posted: 12/20/16 3:44pm Message 15 of 18
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Equinunk, PA - USA
Joined: 10/31/2007
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Vette(s): 1972 conv, 4-speed, 350, 200hp, numbers match, rally wheels, war bonnett yellow w/white top. good condition, nice driver.
Take a GOOD look at the choke. Also, if you can get your hands on the MARCH 2017 issue of VETTE magazine, there is a good article on rebuilding a Q-jet. The cross shafts may need drilling and rebushed. A VERY noted problem after years of wear. It could be sucking air past the shafts and creating a different mixture.


Re: BLOWS BLACK SOOT

Posted: 12/28/16 6:01pm Message 16 of 18
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deforest, WI - USA
Joined: 12/14/2016
Posts: 13
Vette(s): 1981 work in progress
I cant find out how to lean out the carb only info on the net was only about the choke any ideas


Re: BLOWS BLACK SOOT

Posted: 2/15/17 9:28pm Message 17 of 18
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deforest, WI - USA
Joined: 12/14/2016
Posts: 13
Vette(s): 1981 work in progress
OKAY IT WAS THE Q JET THE HOLE TIME IT WAS NEVER REPLACED I THINK THE SHOP JUST SPRAYED SOME CARB CLEANER AND BILLED ME ANYWAY AFTER READING ANYTHING I COULD GET MY HANDS ON THESE 4EME ARE PRETTY SIMPLE TO TUNE BUT THE EASY THING WAS TO JUST UNPLUG M/S AND THE TPS AND SHE RAN GREAT FOR THE FIRST TIME SO THERE WAS THE PROBLEM THE DWELL WAS OUT AND THE VOLTAGE TO TPS WAS WAY HIGH ALSO SET TIMING TO 12 BDC AND 36 ADVANCED VACUUM IS STEADY AT 18 FINALLY NO MORE SOOT NO MORE BLIDING SMOKE


Re: BLOWS BLACK SOOT

Posted: 2/17/17 5:46am Message 18 of 18
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Flanders, NJ - USA
Joined: 1/27/2004
Posts: 2556
Vette(s): 1982 Black, ZZ4, Hooker Side Pipes, 3.55 Rear, Rebuilt & upgraded 700R4, All new suspension, brakes, & new Charcoal interior.
Glad you finally got the issue resolved. Have fun!
Dave



 

Lifetime Member #116
Dave's '82


   

in Forum: C3 Engines


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