How do you clean valves when rebuilding a head?

[bmwpower]

You've seen the black mess hardended on pulled heads...how do you clean this crap off?

[86espowa]

umm, buy new ones?

or use a buffer wheel.

three angle valve job too!

[bmwpower]

umm, buy new ones?

or use a buffer wheel.

three angle valve job too!

Yea, haven't priced new ones. I would guess they're not cheap.

Buffer wheel might do it as long as it doesn't take any metal with it.

[CorvallisBMW]

carb cleaner+brass brush

[SandyEggoE30Girl]

The black mess is better known as CARBON.
If your "rebuilding" a head, you need to take the whole head apart. Then heat tank the steel parts, and carb clean the aluminum head. After that check head for any cracks, surface if needed, replace guides, and the seats if needed. Clean valves with a steel or brass brush, and give the head and valves a three angle cut.
Personally if you have never worked in a machine shop, and do not know how to clean valves, it is better left to a shop that knows what it is doing.

[86espowa]

new valves are just shy of 140 dollars.

[SandyEggoE30Girl]

I would never spend money on new valves unless you have one or some of them burnt, or they have been ground before, and can not be cut again. Also you need to look at the shaft to make sure there is not to much wear there, or galling . A micrometer is always good to use there to make sure the shaft is still good.

[bmwpower]

I would never spend money on new valves unless you have one or some of them burnt, or they have been ground before, and can not be cut again. Also you need to look at the shaft to make sure there is not to much wear there, or galling . A micrometer is always good to use there to make sure the shaft is still good.

Thanks.

What's your definition of a burnt valve?

[SandyEggoE30Girl]

Well this is an extreme case, but none the less, a burnt valve is exactly that.
It could have warpage on it, it could have small cracks in it, or it could have complete sections burned away on the face.

[dkmr]

When I worked at an engine macine shop we used a glass beader to get the carbon off. You just have to be careful about spraying the stems, then grind the seating surface.

[CorvallisBMW]

wow that is one fucked up head....

[NAGROM]

carb cleaner+brass brush

Intake valve 24.35ea
Exhaust valve 60.55ea
from Pacific Motorsports

[StereoInstaller1]

new valves are just shy of 140 dollars.

Where? For all of them, or just one cylinder? You might be thinking Chevy....

[NAGROM]

Where? For all of them, or just one cylinder? You might be thinking Chevy....

Intake valve 24.35ea
Exhaust valve 60.55ea
from Pacific Motorsports (The BMW Shop)

Intake valve 26.70ea
Exhaust valve 66.60ea
from Rasmussen BMW

Im thinking BMW, if I was thinking Chevy I would be on a Chevy site...

[StereoInstaller1]

Intake valve 24.35ea
Exhaust valve 60.55ea
from Pacific Motorsports (The BMW Shop)

Intake valve 26.70ea
Exhaust valve 66.60ea
from Rasmussen BMW

Im thinking BMW, if I was thinking Chevy I would be on a Chevy site...

And your point would be?

"86espowa" said valves are under $140, I was asking HIM where he thinks you can get M20 valves for under $140/set...I know better.

BMA quoted me about $30 each for exhaust, I did not check on intake. Last I checked my math, $140 will not buy exhaust valves, much less a complete set.