Exhaust Manifold turned white

[Dennis/CT]

On the # 2,3,4 exhaust ports my black painted manifold turned white. The #1 port is black. This could be from running lean because I drive with GAV closed ? What else can you think of ? By the way this is a rebuilt engine with less then 300 miles. Carb,dist,gen,starter and water pump are all rebuilt. Thanks to all .

[Blessyouboys]

What black paint did you use on the manifold?

[1963turnerjohn]

Dennis -pull the spark plugs and let us know what they look like - perhaps post a picture of the plugs - this will be a tell-tale on fuel mixture ( rich/lean )

If at all possible - run the car at a speed of say 30MPH while on full throttle kill the ignition, coast to stop, remove plugs - this will give a better indicator of how plugs are acting while in driving condition.

The whitening sounds like heat issue - though plugs will tell the story.

Best,
John

[Mitch//pa]

would also like to know what temp paint you used..

[CarlG]

I used some high priced manifold paint once and it turned white and began flaking after only a few miles. Next time I had the manifold off, I stripped all that off and re-painted it with just plain old Rustoleum BBQ paint. It's still black after a coupld thousand miles.

[Dennis/CT]

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I used Rustoleum BBQ paint

[Napa Skip]

Are there any symptoms of running lean such as backfiring when decelerating?

[Dennis/CT]

Hi, I just pulled the plugs and they all look the same as far as burning,the electrode is on the off white color towards the center of the plug and darker towards the treads.I did have one back fire when shifting gears but not decelerating.

[Napa Skip]

Good point; I should have asked "...when letting off the throttle" rather than "...when decelerating.". Sometimes this can be an indication of running lean. I had never experienced this until another club member complained of violent boiling of the coolant and frequent backfiring when letting off the throttle (such as when shifting). The car was drivable, so he drove it over and when he restarted it and let it idle, the exhaust manifold gradually started turning red. We found that the idle adjusting needle on his carburetor was almost fully shut, and opening it to about 1-1/2 turns open took care of the problem. I thought perhaps a heavy coat of manifold paint might have masked the manifold-turning-red symptom. Just a thought...

[James Rogers]

Adjusting the GAV won't help. It only affects the carb in the first 1/4 of the throttle opening.

[Marco Tahtaras]

Do you ever drive the car after dark? I'll bet the exhaust manifold will glow red in the dark. It's quite a sight! This is usually a combination of running lean and the timing slightly retarded.

[jan bogert]

i'd go to harbor frieght, and get one of those pointer thermomerter, and point it at each exhaust port wile motor is running. and see what temp. is then check timeing, and reset your carb. by richening it some, a little sootie black aint going to hurt.

[Bruce,Upstate NY]

The front of the manifold may be cooled some by the fan, hence the different color.

[Napa Skip]

You don't necessarily have to wait for dark (depending, I suppose, on just how lean the engine is being run). In the example I referred to above, it was broad daylight and there was no doubt in anyone's mind that the exhaust manifold was glowing red, and this at just above idle. Brought new definition to the phrase "Holy glowing exhaust manifold, Batman!" (And we didn't even have any hot dogs to broil...)