Yeah, the original writeup is in the how-to section on my website. I came up with it on my own, but then I had health problems that took me 5 years to sort out, and never tried it myself. Others did and reported back to me that it worked really well. Last year I ran my 261 with the mod for the first time and tested it out on an engine stand. Worked flawlessly and I feel it also improves performance, but like you, cant prove it.
I am pleased you tested it on a complete truck with the wipers because that was a big concern.. was there enough vacuum to do both. Another idea is to use a fuel pump with the vacuum connection, but haven't explored that idea fully. If that worked, that would be a better idea since the hose length would almost be nothing.
