I used a thick wall copper tube and had a machine shop thread the inside of the tube to fit the male threads of my elbow. I J B welded the threads as I screwed it on. Then I tightened the elbow nut down to the copper pipe, again using J B Weld between the nut and the pipe. Let it set for a couple of days. Never had any more problem. If you need the back pressure, you can squeeze the end of the tube until the engine is where you want it. But... the elbow itself might provide enough back pressure. Mine worked fine just running the tube open. You might also try an aluminum tube from Lowe's or Home Depot. They weren't around here when I made mine.

pmw