Can anyone tell me what the proper line size is for a vacuum line from the manifold to the booster? My booster is the Delco 11" stock replacement. The connector for the booster apparently comes in several different line sizes (or at least there seem to be several to choose from at the parts store). The carb base plate has 3 different sizes to choose from as well. Just interested to know what the optimum line size would be.

thanks!

Most that I've seen are 3/8". And they are a special "vacuum" type hose, with reinforcement in the rubber to prevent it from collapsing.

Thanks John. I've tried so many different sizes I just kinda wanted to get back to what was meant for it in the first place. I'm going to T from the manifold and the electric pump into the booster. I'll make sure I get a 3/8" inlet for the booster as well as the pump and T. Then I'll go hunt down some of that reinforced vacuum line - NAPA I imagine.