covey12 wrote:my piston valve will not open when i pilot it it, all of the air comes out of the pilot, which is a 1/4 inch ball valve, on a 2" piston, when i push a stick down the barrel and push the piston back manually, the air does come out
I've recently edited the piston valve page in the wiki to cover many of the common causes of problems in piston valves. Take a look at the bottom of this page and see if anything there can be what you are experiencing.
If anyone else has suggestions on the page edit, please PM me. I am working on getting page creation privileges to create detailed pages on each of the piston formats with photos, math, theory, and construction.