All 8 of the 1/8” lines would not fill up a single 1/16” line. They are 1/8” for easy flow and not restrictive to the injector out flow. But rather than 2 lines back to the tank and into it- they combine into one line. The line is larger than the 1/4” ip return so that it is easier flow to the tank rather than the 1/4” ip return pushing against the injector returns- hence the 5/16 return.
One of the things I wanted to do with a 6.5 is replace the rack style rocker arms with studded ones like the sbc uses. Better individual adjustment to each valve, but this would require more frequent access into the covers for adjustment. Custom valve covers that are cast aluminum (eliminating some of the obvious leaking issues) then the top of the cover would come off for the access.
The injector lines would be in the way, and it’s always been annoying to get them out anyways. So making new lines that go out an around the valve covers was the plan.
In doing all that I was going to run the return lines into the rear where they all would run together already. A db2 has the supply fuel line going up center of the valley already- they get the fuel in where the ds4 has that big harness in the middle of the output lines. So running my ip return line there only made sense, and accomplishing something that bothered me as it does you- that oddball return line going lateral across the front of the engine.
So in case you were wondering why I already had options figured out soon as you asked- I thought these options through about 2 decades ago. But until I could justify the studded rocker arm mounts- none of it was going to happen.
