Smoke from the tailpipe ? help...
Thread Starter
Racer
Joined: Aug 2001
Posts: 310
Likes: 0
From: Tomball Texas
Smoke from the tailpipe ? help...
I have noticed recently my 74 is blowing out just a tad of smoke if I rev the engine 3k-4k rpm and let off sharply. I cant tell if the smoke is black or grey.. The engine has very low miles ( under 15k ) the engine lets off no smoke when started and no smoke at idle, also if I hold the engine steady at 3k-4k no smoke? As soon as I let off sure enough just a brief bit of smoke.. Am I dealing with a carb problem or something more serious??
327 .030
Holley aluminum 67CC heads. 2.02/1.60
Lunati cam .490/.490 1.6 roller rockers
edelbrock intake and 750 CFM Carb.
:confused: :confused:
[Modified by -HIC-, 3:52 AM 10/10/2001]
327 .030
Holley aluminum 67CC heads. 2.02/1.60
Lunati cam .490/.490 1.6 roller rockers
edelbrock intake and 750 CFM Carb.
:confused: :confused:
[Modified by -HIC-, 3:52 AM 10/10/2001]
Burning Brakes
Joined: Aug 2000
Posts: 1,211
Likes: 6
Re: Smoke from the tailpipe ? help... (-HIC-)
I'll take a stab at it. Perhaps it's a bit of oil finding it's way past the rings or perhaps the valves. It's not noticeable at low revs bat it only happens when you let off after revving. Why this might happen and if I'm even remotely close to being right will have to be answered by someone more knowledgeable than me. :chevy
Melting Slicks
Joined: Dec 2000
Posts: 2,041
Likes: 0
From: Wichita, KS
Re: Smoke from the tailpipe ? help... (-HIC-)
Disconnect the vacuum line at the modulator. If it is wet in there, that is your problem. The engine sucks the transmission fluid into the intake manifold during periods of high vacuum (like rapidly getting off the gas), but just lets air bubble past the fluild during normal operation.
Melting Slicks
Joined: Nov 2000
Posts: 2,663
Likes: 3
From: Palm Harbor FL
Re: Smoke from the tailpipe ? help... (-HIC-)
Could it be your carb going temporarily rich on acceleration? Maybe you need to lean out the carb a little. From the symptoms, I don't think it's oil related.
[Modified by 79MakoL82, 9:23 AM 10/10/2001]
[Modified by 79MakoL82, 9:23 AM 10/10/2001]
Burning Brakes
Joined: Jan 2001
Posts: 1,208
Likes: 438
From: Loir Valley Sarthe, France
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2024 C3 of the Year Finalist - Unmodified
2023 C3 of the Year Finalist - Unmodified
Re: Smoke from the tailpipe ? help... (-HIC-)
I've been to the "bad modulator place"!:(
Smoke will usually be pretty grey, almost white. As has been mentioned, it sucks at high vacuum, so you sometimes see it on gearshifts etc. When it gets really bad you canm lay a nice smoke screen down:D Any wetness at the inlet manifold connection will indicate that this is the problem.
May help?
Smoke will usually be pretty grey, almost white. As has been mentioned, it sucks at high vacuum, so you sometimes see it on gearshifts etc. When it gets really bad you canm lay a nice smoke screen down:D Any wetness at the inlet manifold connection will indicate that this is the problem.
May help?
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski