Media blasted valves

[derm.1785]

Hi all, I asked a friend of mine to clean up my badly coked up valves, but on return I see that he has fine media blasted the stem as well, they are only slightly dull but wondered if they are now not usable or can I polish them up as long as they stay within spec or leave alone and fit ?

[john walker's workshop]

Never blast the stems, the guides will potentially wear out. Some do, some don't. Same goes with blasting steel crank gears. The softer aluminum intermediate gear will wear.

[derm.1785]

I thought that might be the case. They are only very slightly cleaned so was hoping to polish them up, is that not an option now.

[Dpmulvan]

Originally Posted by derm.1785

I thought that might be the case. They are only very slightly cleaned so was hoping to polish them up, is that not an option now.

We don’t know what your idea of slightly cleaned is. Can you post some pics?

[derm.1785]

Hi guys. Please see photos, I’ve tried to get as close as I can to show in detail but not sure it helps.

[john walker's workshop]

Junk, unfortunately. Imagine that rubbing inside a soft brass valve guide.

[john walker's workshop]

A bench grinder wire wheel does the job fast enough.

[Dpmulvan]

Pricey mistake

[Walt Fricke]

Otherwise competent shops sometimes do odd things. A shop balancing stock rods (indirectly) for me once ground heavily on the reinforcing rib on the bottom of the cap. Junk. Detroit iron rods had a big pad there to allow grinding it for balance. Not so our 911s.

[john walker's workshop]

Originally Posted by Walt Fricke

Otherwise competent shops sometimes do odd things. A shop balancing stock rods (indirectly) for me once ground heavily on the reinforcing rib on the bottom of the cap. Junk. Detroit iron rods had a big pad there to allow grinding it for balance. Not so our 911s.

Exact thing happened to me years ago. Set of 3.0 rods junk. I swear, if you don't tell them EXACTLY how to do their job and what you expect from them, they'll do something you didn't expect.

[Dpmulvan]

I hate sending anything out gives me anxiety.

[Tonger]

pm sent to op

[derm.1785]

Looks like I’ll learn the hard way, your correct about the necessity to give exact instructions when sending parts out. A lesson learned.

[Walt Fricke]

Don't feel too bad. Most of us have but a fraction of the knowledge, to say nothing of the experience, of John Walker or other professionals who are kind enough to share hard won knowledge. How are we supposed to know the details of the specialist work we are sending out?

At least your new valves will sit higher on their seats, giving you a bit more compression.

[porschetub]

Oh dear,not good,must have been very course media ? .
IMO used exhaust valves are not worth putting back anyway.