when i was changing my springs a bit ago, some valves were much harder to take out or slide down than others, only a few, i cleaned em up best i could , some of them i couldnt even get out, but i could put them back in their original position, none of them stuck where i couldnt get them down at all, but when i tried to get a few all the way out it was like really tough...


will this harm anything when i use the heads?

 

the heads were clean as a whistle cept a few valves had some minor rust which i removed from them..