improper ignition

denpo

denpo

Carburated Nihilist
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Jul 14, 2010
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Montreal, QC
On my way to swap my engine from old frame to the new one, I removed the headers and saw that the cylinder 4 exhaust port is black and greasy, as opposed to the black and powdery of the other ones.
Does is means this cylinder don't have proper ignition, letting the gas leave the engine unburned?
If so this might explain the smelly exhaust fumes.
What do you think?
 
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Greasy/Oily is maybe a valve guide or cylinder that's misfiring quite a bit. Bad plug, plug wire, cap would be the first things I'd look at, followed by compression test and leak down test. Simple/easy/cheap stuff first.

And how bad is it? A little bit? Or really nasty to the point of oil should be running out the exhaust?

#4 cylinder is toward the front, so that takes any chance of the vacuum system sucking oil away.
 
TimAT said:
And how bad is it? A little bit? Or really nasty to the point of oil should be running out the exhaust?

#4 cylinder is toward the front, so that takes any chance of the vacuum system sucking oil away.
Click to expand...
I say it's a little bad.
Here's a picture of it :
16554ccf7eb4a8226.jpg

vacuum system sucking oil away? Duh, I guess I'll have to study that SBC tech book deeper :noob:
As always, thanks a lot.
 
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Sorry, poor choice of words.. The PCV system can suck oil away, but it usually dumps it into the center of the intake and it gets thru all cylinders pretty evenly. The automatic trans cars can also get oil from the trans modulator that's in the intake over cylinders 6-8, but that drops right into the intake runner and gets only those 2.

From your picture, I'd have to say just maybe the valve guide on that cylinder is a bit loose or a remote possibility the rings are passing a touch of oil.
Look at the spark plug- if it's pretty clean, put this one on the "look at it later" list.
 
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