Thanks for your reply. So will unlead petroleum can act like the gas in your a/c system. After it comes out of the small orifice the gas expands and gets cold. So at the moment, i have air and fuel going through the carburetor (dont know the size of the hole that goes through the carburetor) out to my device, witch has a slightly bigger pipe then to the engine. My device has the same in and out diameter pipe. So will this cause the pressure drop. My carburetors hole through the center is about 18mm and my device has 19mm. Hiw much will this effect it.
Sorry for lack of info. It would be easier if i could tell you what my idea is, but i need to know why the fuel and my devise gets so cold.