If your using good quality black fuel line like continental then I wouldn’t worry about testing the connections for leaks. That hose fits so tightly I swear you could get away with having no clamps at all. The machines I have worked in were all 1/4” ID. Youre is a 951 so I’m pretty sure a lot of those fuel lines are 5/16” and some 1/4” on it as well but no idea where. I usually vacuum test the fuel selector and the fuel filter strainer on there own. 4 pounds of vacuum is good. If your using a mityvac be careful of sucking fuel into it, I damaged my first one by doing this. Are you using good quality black line or cheaper clear line? If you’re using the clear, go to the automotive store and buy a foot of quality black line and you will see the difference in how they snug on to the fittings.
