dreadpirateroberts

iTrader: (1)

Bought a set of heads off of ebay, heads themselves look ok, seats look decent, maybe worn but no pitting, and guide clearance checks out.

almost every intake valve had this horrible pitting on the heads of the valves. they don't look like deposits of any kind, and i couldn't imagine they were cast this poorly. the bottom of the heads are actually fine and look nothing like this. valve faces are also worn, very slightly concave.

What say ye, ls1tech? what could have caused this, and are these still usable?

dreadpirateroberts

iTrader: (1)

actually, with the wear, the margin would probably be non-existant if they were refaced...

all the same, still curious as to what could have caused the pitting.

onebadbowtie86

iTrader: (13)

Did they sit in a junk yard with water on them/rust.

sjsingle1

iTrader: (1)

valves are not to expensive.......i would not use those

LLLosingit

iTrader: (4)

That's to much pitting to blame on fuel, Must have been a manufacturing issue.

dreadpirateroberts

iTrader: (1)

makes me wonder about the kind of QC they used when they cast them.

someone also mentioned that chlorine can cause the stainless steel to pit. I'm sure other chemicals can as well. wonder if something corrosive would be the cause? if so, how did it did it get in there?

Enigma540

I'd go with this. Looks like they were rusted horribly, then wire wheel'd to clean them up. No matter what happened to them, the way that pitting run up into the transition to the stem........I wouldn't run them in the cheapest "I don't care about it" build one could dream up.

dreadpirateroberts

iTrader: (1)

No, they weren't wire wheeled. Carbon and varnish was cleaned off with some solvent and that was it.

there's no corossion on the stems. It all starts right at the filet and is all over the head. Some are worse than others.

Enigma540

i didn't mean up on the stem, just right up on the curve where the head transitions into the stem. That's a very high stress area and those are pretty chewed up right in that curve. I'd junk them and if you're on a budget find some better factory replacements or go with like a rev brand or something. No way I'd run those.

mintws6

Looks a lot like chloride corrosion/pitting, possibly some under deposit/crevice corrosion. Wouldn't run those valves.

dreadpirateroberts

iTrader: (1)

you don't have to try to convince me to not use them anymore. I decided that in post 2 anyway, although for a different reason.

my response was in line with finding an answer as to why they pitted. I don't believe it was from water sitting in the ports, unless it was saltwater. Even then... there was no rust on the valves. Just carbon and varnish, like i said. Unless the previous owner cleaned them up and used them.

WELL i guess LLLosing it and my other associate have the best theories as to why stainless intake valves would pit like this.

Thanks anyway.

dreadpirateroberts

iTrader: (1)

Another vote for chloride corrosion, which would actually make sense. Thanks!

The question is... chloride from what? Did some idiot pour bleach in the intake ports, lol?

mintws6

You can have a build up of chlorides simply from the environment, due to where the crevice sealing surface is and the carbon build up mentioned I suspect that the gasoline/ethanol sulfate salts concentrated these contain chlorides. These under deposit chlorides accelerated the corrosion of the stainless material. I see these types of things in chemical plants all the time. Under deposit corrosion is what created the severity of this corrosion. I would bet those heads sat for a while.

RB04Av

Yup, just typical chemical erosion on cheeeeeep stock valves. Nothing to see here. There are all sorts of things that they put in gasoline besides the pure hydrocarbons.

00pooterSS

iTrader: (40)

Those are dimpled for fuel atomization! lol

If anyone remembers the dimpling craze you'll know what I'm talking about

dreadpirateroberts

iTrader: (1)

Wow. Interesting theory. So whoever had these basically had really poor gas quality.

The cheeeep stock valves are better than some aftermarket trash out there.

dimpled for moar CFM's of uurrrflow.

RonSSNova

iTrader: (3)

It works for golf *****.....

RB04Av

Ain't that the truth. Seems like no matter how crappy something is, somebody can come up with a way to somehow make one even crappier.

dreadpirateroberts

iTrader: (1)

speedmaster?