One side of motor stoich and one lean?
Thread Starter
Senior Member
Joined: Nov 2005
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From: Tolland, CT
Car: '86 Camaro SC
One side of motor stoich and one lean?
I went to pull my plugs the other day. I noticed cylinders 1, 3 were lean (slight white coloring on the tips) and 2,4 were perfect (tanish color on tips). My question is, why would one side of the motor run lean and one side perfect? Is there anyway to fix this?
The carb is an Edlebrock Performer part # 1406. It still has the stock calibration on it.
The carb is an Edlebrock Performer part # 1406. It still has the stock calibration on it.
Supreme Member
Joined: Sep 1999
Posts: 7,072
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From: Philly, PA
Coupla things.....
1. No carb is perfect, but they're usually plenty close to perfect unless there are real problems.
2. No intake manifold has perfect mixture distribution, but again, they're usually plenty close to perfect unless you've got vacuum leaks (intake gaskets, vacuum ports that go to the carb or intake, etc.). If you're using a dual plane intake then 2&4 and 1 &3 are on different planes of the intake anyway and don't feed off the same side of the carb. 1&4 and 2&3 share the same planes on a dual plane intake. On a single plane, yes, you could have one side of the car running rich and the other running lean causing the side-to-side difference you are seeing.
3. Not all plug coloration comes from the combustions of air and fuel. Just a little bit of oil coming past the valve guides or rings can give you that nice tan coloration. Obviously, lots of oil will turn it black but there's a million shades in between.
Not an answer, but hopefully this helps.
1. No carb is perfect, but they're usually plenty close to perfect unless there are real problems.
2. No intake manifold has perfect mixture distribution, but again, they're usually plenty close to perfect unless you've got vacuum leaks (intake gaskets, vacuum ports that go to the carb or intake, etc.). If you're using a dual plane intake then 2&4 and 1 &3 are on different planes of the intake anyway and don't feed off the same side of the carb. 1&4 and 2&3 share the same planes on a dual plane intake. On a single plane, yes, you could have one side of the car running rich and the other running lean causing the side-to-side difference you are seeing.
3. Not all plug coloration comes from the combustions of air and fuel. Just a little bit of oil coming past the valve guides or rings can give you that nice tan coloration. Obviously, lots of oil will turn it black but there's a million shades in between.
Not an answer, but hopefully this helps.
Joined: Jul 1999
Posts: 12,093
Likes: 126
From: SALEM, NH
Car: '88 Formula
Engine: LC9
Transmission: 4L60E
Axle/Gears: 3.89 9"
Originally posted by Damon
Coupla things.....
1. No carb is perfect, but they're usually plenty close to perfect unless there are real problems.
2. No intake manifold has perfect mixture distribution, but again, they're usually plenty close to perfect unless you've got vacuum leaks (intake gaskets, vacuum ports that go to the carb or intake, etc.). If you're using a dual plane intake then 2&4 and 1 &3 are on different planes of the intake anyway and don't feed off the same side of the carb. 1&4 and 2&3 share the same planes on a dual plane intake. On a single plane, yes, you could have one side of the car running rich and the other running lean causing the side-to-side difference you are seeing.
3. Not all plug coloration comes from the combustions of air and fuel. Just a little bit of oil coming past the valve guides or rings can give you that nice tan coloration. Obviously, lots of oil will turn it black but there's a million shades in between.
Not an answer, but hopefully this helps.
Coupla things.....
1. No carb is perfect, but they're usually plenty close to perfect unless there are real problems.
2. No intake manifold has perfect mixture distribution, but again, they're usually plenty close to perfect unless you've got vacuum leaks (intake gaskets, vacuum ports that go to the carb or intake, etc.). If you're using a dual plane intake then 2&4 and 1 &3 are on different planes of the intake anyway and don't feed off the same side of the carb. 1&4 and 2&3 share the same planes on a dual plane intake. On a single plane, yes, you could have one side of the car running rich and the other running lean causing the side-to-side difference you are seeing.
3. Not all plug coloration comes from the combustions of air and fuel. Just a little bit of oil coming past the valve guides or rings can give you that nice tan coloration. Obviously, lots of oil will turn it black but there's a million shades in between.
Not an answer, but hopefully this helps.
-- Joe
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Joined: Jan 2000
Posts: 19,659
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Hey, Whalers Fans.
Are both heads the same? There have been more than just a few isolated incidents of mixed heads on an engine.
Unless your intake is very unconventional, it likely isn't the carb. On single plenum intakes, mixture is shared enough to minimize such a difference from side to side. On dual-plane intakes, alternate runners are usually fed from alternate sides of the intake, so that all the plugs in one bank would not read the same - It would be more half and half on each side.
Are both heads the same? There have been more than just a few isolated incidents of mixed heads on an engine.
Unless your intake is very unconventional, it likely isn't the carb. On single plenum intakes, mixture is shared enough to minimize such a difference from side to side. On dual-plane intakes, alternate runners are usually fed from alternate sides of the intake, so that all the plugs in one bank would not read the same - It would be more half and half on each side.
Thread Starter
Senior Member
Joined: Nov 2005
Posts: 577
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From: Tolland, CT
Car: '86 Camaro SC
Both heads are the same, 2.02 GM cast iron pieces. The intake is a dual plane, Edelbrock. I know that different sides are fed from different parts of the intake, but what would I adjust to compensate for one side being a tad lean (or appearing to be) and one being good?
-Thanks, Brandon
-Thanks, Brandon
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