Cylinder bore/clearance

[chet1185]

I need some help.

Just removed the engine to do a cam and all supporting parts. After removing the heads I saw that the pistons are covered In black stuff.

The engine has like 10k miles. The heads were reused. Never touched. Could the valve seals be bad allowing oil into the cylinders?

The engine was bored .030. Someone told me I probably have piston slap. And the piston to bore clearance isn't right. I'm not an engine builder but I remember when I measured, the ring clearance was perfect. Cross hatch looks good in all 8 cylinders.

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[firebird_1995]

Could be from a few things. Could be from a bad or missing pcv valve, bad valve seals, bad rings.
What do the back side of the intake valves look like?
Are the intake ports covered in oil?
How was the compression?

[chet1185]

Valves look good. Nice and clean. I'll look at the intake

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[chet1185]

Pretty dry inside.

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[firebird_1995]

Does every piston look the same?

[firebird_1995]

If an intake valve stem was leaking I would expect to see oily carbon buildup on the stem and back. If the oil was coming in through the pcv system you would see it on the floor of the intake ports. Another place of entry I've seen the intake gasket between the port floor and lifter valley area. When you take the intake off you would have to look for oil on the sealing surface of the gasket/head/intake area. With the amount of build up on those pistons I would think that there should be evidence on the valves too.
Are you confident that the rings were seated?
Grit of hone used for the rings was correct?
Was there any issue at startup that could have washed the rings?

[chet1185]

I did the break in, I'm guessing it was fine. All pistons look like that. Someone said it's just carbon build up??

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[chet1185]

On the exhaust ports under the valve they're is allot of carbon flaking off. Maybe that's what it is?

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[firebird_1995]

I think the buildup you're seeing on the exhaust valves is what was getting pushed out of the cylinder. It is carbon buildup but there is quite a bit of it, and for 10k I think it is pretty excessive. If you feel good about the health of the bottom end and it wasn't drinking oil then clean it up and let it eat. I'd go ahead and get a compression test after you get it together as a baseline for future reference

[chet1185]

Thanks man. I'll do test once it's done.

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