Valve Coating?

[Crossrodes]

I noticed when I cleaned up my heads and piston on my '79 that below the black carbon that I had to clean off there was what appeared to be a grey coating on the exhaust valves.  Is this a coating put on to dissipate heat or what is it?

[Lucky_Lou]

do you have an image?? do you use a fuel adative??
Lou

[Justin B.]

I don't know if it would be a coating or surface finish, especially without seeing it...

[Crossrodes]

I have a photo now that shows the "coating on a valve".  The question now is how do I post this image? :-/

[Justin B.]

just click the browse button next to one of the attachment slots and click on the pic you want to attach.

[Lucky_Lou]

my head looked like this when i stripped it just carbonized gunk
Lou

[Crossrodes]

OK here's the photo...hope this works:

Youcan see what appears to be a crust on the valve.  This is not carbon as it is a different colour (grey).  I've removed most of the carbon.  So what is your guess as to what this is and should I remove it?

[nhmaf]

Hmm, the valve face looks more like it is eroded, or indented, to me rather than having something stuck on it..

[Justin B.]

If you take something like a scribe and scratch both the raised and eroded portions is it shiny/silvery underneath?

[vestandpants]

The heads shouldnt be too difficult to clean up. Mine looked like this when I stripped them :

http://www.flickr.com/photos/22686607@N06/2451725164/in/set-72157604788162024/

The valves had a similar coating on them. I think its just years of use matey because given the right treatment they look like this:

http://www.flickr.com/photos/22686607@N06/2619984497/in/set-72157605872982912/

Now, I sent my heads off to have the exhaust valve seats replaced aka unleaded conversion, and I sent the valves etc with them. the firm cleaned the valves up for me before grinding them in and building them up to the standard you see. The valves you see in the picture are the same ones from the first picture.

[Crossrodes]

Thanks for the feedback guys.  Masoon I think you nailed it.  I'll go ahead and remove this crud.

Mike

PS: What part of Cheshire are you from?  I used to live in Huyton, Nr Liverpool and spent lots of weekends in Wallasey in the summer.  I now live in Canada.