Kody was over today and I had him help makeup these parts. I've been thinking about the fuel vent fittings and wanted to make sure that my new design didn't adversely affect the operation. Essentially the fittings need to create a bit of positive pressure for the tanks by pointing into the wind. I decided to test the fitting with a manometer.

Here's the test rig. Kody's hanging it out the window to demonstrate how this will work. There are two holes in this piece of plywood. One hole is flush with the surface. The other hole has the fitting installed. There is a piece of clear tubing used for the manometer. It attaches to one of the ports, comes inside the car and makes a U loop (which has water in it), and goes back out to the other port. If the fitting is creating positive pressure, it'll push the water level down in the side of the U loop attached to the fitting.

Here's an closeup picture. You can see the flush port about two inches to the left of the fitting. This rig worked great and confirmed that the new design does indeed still make positive pressure. At 60 MPH there is about 1 inch H₂O pressure differential between the two ports.