I was just reading this in another post and had a couple questions.
The redish deposits are normal with todays gas. If money is short, have a machine shop ck the guides and seals. O-ring and umbrella seals are things of the past. Positive seals are much better and will do a good job even with increased stem to guide clearances. The pistons and rings may last a while longer, but its pretty much a crap shoot.
I'm not very familiar with different types of valve seals I was just wondering what the difference between o-ring seals, umbrella seals, and positive pressure seals were. What are the disadvantages/advantages of each were, and if you had to do anything special to the heads to install positive pressure seals. Just thought I'd ask, thanks.