Ok, I know this sounds simple but I was installing the new venturi and spraybar in my os .25 LA. I have a hard time trying to get it snug and was wondering what You all use to hold and tighten the spraybar and the nut ? I do not have any open ends that small and my sockets wount go over the spraybar.

Sears sells Craftsman midget combination wrenches in SAE and metric.  With a set of each, and fairly complete sets of metric and SAE 1/4" drive sockets, most of the time I've got the right tools for the job.  Sometimes it's easier to use a hemostat or needle nose pliers on the spring side.  It can be difficult to get the tools in around the spring, and it doesn't take much force to get the spraybar tight.

I think 5.5 mm is the correct size. I ground one socket down to where it would fit between the springs without spreading them apart very much.