valve coating?

[91greensho+]

I am in the process of rebuilding my heads and would like to know if the valves were coated in some sort of black stuff from the neck down. If so, can they be wire wheeled and cleaned up or is it just very stubborn carbon?

 

[91greensho+]

no body has ever rebuilt a sho head before? i find that hard to believe

 

[Mr Anonymous]

The valves were chrome plated when new. If you're intent on cleaning the valves, put a length of hose down the stem until the step (to protect the stem), and then use glass bead in a blast cabinet to clean them. Most other medias will remove metal, glass bead will not.

 

[AREA 91]

The valves are usually covered in carbon from the "neck" down. I placed my valves in a pan of berrymans B12 to soak overnight, then used a wire wheel to remove the gunk.

 

[91greensho+]

thanks, i didn't know if a wire wheel was the best way to do it or not

 

[shoebilly]

thanks, i didn't know if a wire wheel was the best way to do it or not

A wire wheel works well, will not damage the valve I did this to a 200000mi head and the valves were in perfect condition other than the gunk & carbon they cleaned up well & I lapped them in & resealed them and have had no problems. The oem valves & springs hold up very well.

 

[zuup_2000]

Ive always wrapped the stem with something and placed it in a drill press. It makes removal of carbon much easier. If you have a large amount of build up, you can use the tip of a flat head screw driver to run across it as it spins in the drill chuck, just dont bear down on it with extreme pressure. Then I always finish with a piece of scotch bright. It works better to have the valve dry, and not use any type of cleaner (plus the cleaner just gets slung off anyway). Then you can lapp them and call it a day. The valves are very hard, so you shouldnt be too worried about damaging them if you use some common sense. Ive done MANY head rebuilds using this method and have never had a valve get damaged, or give me problems later on.
Some folks say that lapping is a bad thing, and its old practice, but I feel its great for a person that cant afford a good valve job. It is a great improvement compared to leaving them as is. If you do decide to lapp them, its very important to make sure the valve stem, and vlave guide are free of any dirt. I keep a supply of brake cleaner as a rinse for parts, and it works great for this type of thing. You can spray out the guide your focusing on, and spray off the stem, **** it and get to lapping.
Oh well, Ill stop rambling, just figured Id throw some ideas at ya.

 

[91greensho+]

thanks for the imput