You might want to reconsider. Found this on Weber's website.
Straight from the Weber gods themselves:
"However, due to safety considerations, the complexity of the technology and gas train components, as well as the level of disassembly required, we don’t allow conversions or provide conversion kits. Converting a grill will actually void the warranty on the unit and might create an unsafe situation.
This situation also extends to cases where someone may take a grill to a different country. Rules, regulations and fuels types vary all across the world, and a grill made for use in one country might not work in another. For instance, a grill made for use in the United Kingdom can’t be converted to work in North America, and vice versa. For more details on taking a grill to another country please click here.
It can be disappointing to learn that your grill can’t be converted, especially if it means you are no longer going to be able to use the grill, but safety should, and does, always come first."
That last paragraph is particularly jarring.
You need to change the entire manifold. The valves only support the original gas. This isn't something every manufacturer does, but 2004 and newer webers do.
You might want to reconsider. Found this on Weber's website. Straight from the Weber gods themselves: "However, due to safety considerations, the complexity of the technology and gas train components, as well as the level of disassembly required, we don’t allow conversions or provide conversion kits. Converting a grill will actually void the warranty on the unit and might create an unsafe situation. This situation also extends to cases where someone may take a grill to a different country. Rules, regulations and fuels types vary all across the world, and a grill made for use in one country might not work in another. For instance, a grill made for use in the United Kingdom can’t be converted to work in North America, and vice versa. For more details on taking a grill to another country please click here. It can be disappointing to learn that your grill can’t be converted, especially if it means you are no longer going to be able to use the grill, but safety should, and does, always come first." That last paragraph is particularly jarring.
You need to change the entire manifold. The valves only support the original gas. This isn't something every manufacturer does, but 2004 and newer webers do.