The process I used to create this master vac hose section is something I learned from Kats. Kats used braided fuel hose which is the exact correct size, but
much softer than rubber vacuum tubing, and brass rod to give the hose perminent shape.
I used 11/32" ID brake vacuum hose from NAPA AUTO PARTS which is an exact match in size and texture to the Nissan hose, and 1/4" copper refrigerant
tubing from Home Depot. Using a length of the copper tubing, I shaped it first and then slid the rubber hose over the tubing. A little sil-glyde on the tubing
made the process fairly smooth but guard against using excessive pressure that might kink the copper tubing.
Before inserting the copper tubing, you must cut enough off of each end of the copper tubing, one to one and a half inches, to allow room for the master vac,
check valve, or engine mounting fitting in the rubber tubing. I, also, leave an extra 1/2" or so on the rubber tubing that can later be trimmed for a perfect fit.
I plan to make a compete set of these master vac hoses and will take all the measurments for those who might want to try this for there own project.
I'll try to attach the reference to Kats posting.
http://www.classiczcars.com/topic/23900-datsun-240z-vs-fairlady-z432/page-8
Look at post #154 on this page.
Let me know if there are any questions as to how I made this hose.
And, yes, the copper tubing remains in the vacuum hose to maintain the shape.
Dan