I can tell you my experience in Tech and I learned something. My vent consisted of a 1/2 tube coming out the top of the tank wiht a loop coil, a right angle down, exiting out of the bottom of the trunk with a check ball fitting mounted on the bulkhead fitting on the outside of the trunk sheet metal. The car had passed tech at el Mirage with the previous owner so I did not put much thought into it. When I got to SpeedWeek tech the inspector showed me where that set up would work fine if the car landed on it's roof and fine if it landed on the driver's door. But the vent was on the right hand side of the fuel cell. If it ended up tipped up on the passenger door fuel would siphen out because the vent was now the lowest side of the tank. We added another right angle and took the vent to about 2" past the left side of the tank where it would be would always be at the highest point if the car ended up on either left or right door.
Visualize the car sitting on its roof, left or right door. If the vent opening is the lowest point of the tank it will siphen. That's my non-engineer explanation. I am sure there are others that can articulate it better. I zip tied a piece of scotch pad around the vent to limit the salt and crud from entering the check ball.
Bill