It would seem like gas caps need two valves to maintain proper pressure. One to relieve over pressurization do to expansion and the other to eliminate negative pressurization when engine fuel pump is running. Just a hole in the cap allows vapors to escape, although minimal, still a dangerous combustible in a confined garage.
That is why I recommended only a 1/8" hole.
These new caps are not designed correctly and do not allow the tank to adequately breathe in or out.
The original caps were designed to breathe.
Do I know that a 1/8" hole is the perfect amount of air, duplicating the design of the original cap? No.
After I drilled 4 different caps on 4 different trucks with a 1/8" hole, upon removing the cap, I no longer hear the sound of significant vacuum, nor the sound of pressure release.
If one was more comfortable with a 1/16" hole rather than 1/8" hole to ease their mind concerning the possibility of too much venting, I have no argument against that.
Two of my trucks, which are kept inside, with 1/8" vent holes drilled in their new caps do not cause any discernible odor of gas inside of my garage.
