Usually you can take the tank off and stick an open end 15/16" wrench in and take it off. To adjust the valve, loosen the nut with a 10mm wrench and hold a screwdriver sideways or think of something to turn the screw. An adjusting wrench might be worth getting if you work on your motor a lot, or have multiple machines. As for a feeler gauge, they are definately worth getting, they are cheap and can be used in many places.
-Nick
1988 Chevy Silverado 5.9L Cummins : 1986 ATC250R : 2012 Polaris RZR 570 :
98% of Americans say 'OH $#!T!!' before going into a ditch on an icy road. The other 2% are Alaskans, and they say 'Here, hold my beer and watch this!!'