the plug gap is the gap between the center electrode and the ground electrode on the spark plug. The center electrode is the part that comes out of the center of the plug at the bottom and the ground electrode is the tang that's at the bottom of the plug.
set the gap between the 2 at 28-30 thousandths of an inch.
you will need a spark plug gap tool to do this, but you can get them at any auto parts store for about $1.00.
If this gap is too wide, it's hard for the ignition to make the plug spark.
if this gap is too narrow, you will get spark, but it won't be good enough.
what "va;ve" are you talking about? do you mean the intake tube?
the part that bolts to the engine where the carb connects to?
the gasket is nothing more than cardboard, and you will either have to make a new one out of gasket material, or buy a new one.
to be honest, it's cheaper to just go and buy a sheet of gasket material from the auto parts store and make your own.
use the flange on the intake tube to draw out the shape and then cut out your gasket with some scissors or a razor blade.
don't get cork gasket, get something rubberized that is made for carburetors.
