I bought a rebuildable 350 Vortec ( 2000 engine out of a 3/4 ton fleet truck ) The previous owner said he replaced the engine due to a "Stretched Valve". ??? Never heard that term before.
I started a tear down today and am down to the bottom end. I can find nothing that would suggest a valve train malfunction. I have to buy a balancer puller to go any further. I'm suspect of a wiped cam but the lifters are clean and free. Rollers are not worn or scuffed. Cyl walls still show cross hatch marks.
If anyone knows what a "Stretched Valve" is I sure would like to know.

 

Thanks for all the help...I found the info I needed elsewhere...

 

I have not heard that term used in years, probably because it dosen't happen. If you bought a rebuild core, that's one thing you should address. So, if you are going to rebuild it, great. I didn't post because as stated that's one area you would address. I should have re-read your post asking what a stretched valve was, sorry. I'd recommend either replacing the heads, or send it to a machine shop with valves, and valve guides.