1973 corvette exhaust smoke
Thread Starter
Intermediate
Joined: Mar 2022
Posts: 33
Likes: 1
1973 corvette exhaust smoke
I have a 1973 Corvette L48 with around 80k miles. The bottom end should be stock but I have Edelbrock E-Street 64cc heads, Comp Cams 268h xe cam (Lift: .477''/.480'' Duration: 268°/280°), 1.5 Roller rockers, HEI distributor, Edelbrock EPS intake, and an Edelbrock AVS2 650 cfm carb. I thought that I was fighting the car running rich as the car was fouling out plugs in about 10 minutes of driving. At idle the car doesn't smoke at all, it smokes slightly when the throttle is applied and mostly when the throttle is let off. I can't tell if the car is still running rich after stepping down the metering rods, or if I'm burning oil, or something else causing the car to smoke and the plugs to foul out.
Thread Starter
Intermediate
Joined: Mar 2022
Posts: 33
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I have had the car for about 2 years now and did the heads and other upgrades about a year ago. The bottom end has at most 90k miles but I bought the car from someone who didn't know much about the car. He mentioned something about work being done to the bottom end but when I was in there I didn't find any obvious changes.
Melting Slicks
Joined: Nov 2006
Posts: 3,416
Likes: 1,825
From: Apple Valley, MN
Ok, so how did the car run right after you installed the heads? Has it exhibited the problem ever since or has it manifested recently?
What color is the smoke?
Do you know how to “read” spark plugs?
What color is the smoke?
Do you know how to “read” spark plugs?
Race Director
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From: Sunshine Coast, Queensland, Australia
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Bad intake manifold gaskets pulling oil from the valley into the ports? World's worst carburetor? All 8 plugs black? Just a few? Color of the smoke? Etc. Etc.
Race Director
Joined: Mar 2016
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From: Napa Valley California
Automatic transmission?
If the smoke is light grey, or white, check the vacuum module at the transmission.
If the module went bad, the engine could be pulling transmission fluid into the intake and into the cylinders.
Check to see if your transmission fluid is low.
Module is about $10.00.
If the smoke is light grey, or white, check the vacuum module at the transmission.
If the module went bad, the engine could be pulling transmission fluid into the intake and into the cylinders.
Check to see if your transmission fluid is low.
Module is about $10.00.
Thread Starter
Intermediate
Joined: Mar 2022
Posts: 33
Likes: 1
Automatic transmission?
If the smoke is light grey, or white, check the vacuum module at the transmission.
If the module went bad, the engine could be pulling transmission fluid into the intake and into the cylinders.
Check to see if your transmission fluid is low.
Module is about $10.00.
If the smoke is light grey, or white, check the vacuum module at the transmission.
If the module went bad, the engine could be pulling transmission fluid into the intake and into the cylinders.
Check to see if your transmission fluid is low.
Module is about $10.00.
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Thread Starter
Intermediate
Joined: Mar 2022
Posts: 33
Likes: 1
The smoke has been getting worse as of late, there has always been some but it seems to be more now. I was fighting a fuel mixture issue for awhile so I thought it might be related, but the smoke is white which wouldn’t make sense for a mixture issue. The spark plugs are definitely fouled, they seem oily but I can’t completely tell.
Old Pro Solo Guy
Joined: Dec 2017
Posts: 8,103
Likes: 4,463
From: Marlton NJ
Hmm fouling plugs and white smoke...
I would do some basic tests:
I would do some basic tests:
- run compression test
- run a leak down test
- run a coolant combustion test
Race Director
Joined: Mar 2016
Posts: 14,423
Likes: 8,231
From: Napa Valley California
Could be a head gasket leaking water and anti freeze into one or more cylinders.
How does the oil look?
You may or may not see milk shake oil but the tests Leigh recommended above should help you solve the riddle.
How does the oil look?
You may or may not see milk shake oil but the tests Leigh recommended above should help you solve the riddle.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Sounds like a head gasket leak or an intake manifold leak. If the 'smoke' is white, you are likely seeing coolant leakage; if it is grey, likely oil. If plugs are fouling, most likely oil leakage into the intake manifold.